Many of these have been answered, but I'd like to give my take on them anyway where I think it could be helpful. I tend to get long winded some times, so sorry about that.
- It looks to me that in O that there is no universal remote and each of the systems are proprietary, meaning that DCS only works with MTH locos, LionChief+ with Lionel, etc., correct?
This is pretty well correct, but is not especially problematic for most folks. Generally people will choose one system to start with, based on what engines they own already, or plan to own in the future. Then at some point will add the competing system. Following is just a brief bit of information on the systems, since it seems you are a bit confused here, and it sounds like you might not have a good grasp on the different systems offered by Lionel.
Conventional - (Runs all engines of all manufactures(Special note on LionChief))
Two wires and a transformer, your basic set up with a transformer throttle, whistle, and maybe a bell. This control system will run all brands and products that I am aware of in O-gauge, with one "sort-of" exception in the LionChief line of products. See the LionChief description below.
Lionel, TMCC - (Runs TMCC equipped engines, Also runs limited features of Legacy engines, Can control conventional with additional hardware.)
TrainMaster Command Control is the first system for advanced multi-function control, released in the mid 90's by Lionel. The system is still in wide use today, and engines that operate on this system are still produced by other manufacturers, as well as being an openly licensed system in the past. You'll find K-line, Atlas, Etc all with TMCC operation. In addition the ERR sells boards that allow you to upgrade most any conventional engine to TMCC. The TMCC system will only run TMCC equipped engines right out of the box(As well as a limited feature set on Legacy engines), but the product line offers additional items that will allow you to operate conventional engines from the remote. Other additional add-ons will allow control of switches, accessories un-coupling tracks, and the like from the remote. TMCC will also allow basic control of Legacy locomotives, limited to only the features that exist in the original TMCC.
Lionel, Legacy - (Runs all Legacy and TMCC products, Can run conventional with additional hardware.)
Legacy is Lionel's second generation of command control. Released in about 2006, Legacy is 100% (as far as I know) backwards compatible with TMCC, meaning it will operate any TMCC equipped device or engine. In addition the new system provides a number of more advanced features, and a remote that allows better control and stores more information. Legacy equipped locomotives have a larger set of features than their TMCC counterparts, and typically out-perform TMCC in every way. At this time there is no offering for a Legacy upgrade kit on the market, and given the particulars of the system that give it the added benefits, it is unlikely we will see such a kit.
Lionel, LionChief/LionChief Plus - (Runs along side any other system, but can only be controlled by their own matched remote. [Or conventional on LC+])
LionChief and LionChief Plus, hereafter referred to as LC and LC+, almost deserve two separate descriptions. LC was released as an entry level product in 2013 followed in 2014 by LC+ which addressed one major issue many had with the original as well as adding a host of additional features. LC/LC+ engines can be run on the same track as any other engine or while any other control system is in place, but they can only be controlled remotely from their matched remotes. original LionChief can ONLY be controlled from it's remote, where as LC+ can be switched to conventional mode, allowing it to operate like any other conventional engine. Both Lc and LC+ use the same style of wireless remote, with one remote used for each type of engine (If you have two of the same engine, even with different road names, a single remote will control both of them. Good for double heading, bad for running separate trains.) The remotes allow forward/reverse speed control, whistle/horn, bell, and crew announcements control. In addition, LC+ uses a quick double press of the horn/bell buttons to fire front or rear electrocouplers. LC+ also offers steady speed cruise control and better sounds that LC. At this time Lionel has promised a remote that will run up to 3 LC/+ engines, but it has not yet been released.
MTH, DCS - (Runs DCS and conventional out of the box, Can be connected to a TMCC/Legacy system for basic TMCC control)
I believe DSC was introduced around 2001 (I couldn't find the date with a quick search of the net.) by MTH. When it was released it was billed as a superior system to TMCC, and the answer as to which is better today between Lionel and MTH's system will give you as many answers as people you ask. Much like Legacy, DCS will only allow it's full set of features to be utilized with DCS locomotives, however it can be used to control conventional engines right out of the box. In addition, if you already have TMCC you can connect the DCS TIU to the TMCC base with a cable and the DCS remote can then be used to control TMCC functions. It IS a misconception that DCS can actually control TMCC, it can only talk to a properly functioning TMCC system. At this time, DSC does not have access to Legacy-only features. In addition, the latest line of engines equipped with DCS also come with DCC capability for use in 2-rail operation.
TMCC-Legacy, DCS, and LionChief can all be used at the same time on a layout to operate their engines, and for the most part wont cause each other any problems. DCS can be finicky but there is a bunch of 3rd party material out there that can guide you through this, as well as abundant information here on the forum. Tmcc/Legacy can also have signal issues on multi level layouts that can likewise be solved pretty easily.
- So therefore, I will have to get a control system from MTH, Lionel, Bachmann (aka lots of $$$$) so that I run locos from each company?
- Or am I pigeonholed into buying locos from one manufacturer only and stick with them until eternity? I hope not.
Well yes, from Lionel and MTH if you want full control of all the features of all the engines on the market, however most people will chose one to start with. I am Biased toward one more than the other, but people generally choose based on what brand offers more products they are expecting to purchase in the near future, then add the other system at a later date. worth noting that LC/LC+ doesn't care what system you are running. As for it being lots of $$$, yes, each command system costs several hundred dollars, but if you compare that to the costs of the locomotives you are operating, it is only a small fraction of the money you will put into this hobby. If your budget really is a significant factor, as it is for me, you may want to look into purchasing a used TMCC system to start, then add DCS and/or upgrade to Legacy at a later date if your budget allows. I believe I paid $60 for my used TMCC base and remote.
- Can my older locos be made remote compatible by simply adding a decoder chip?
Sort of. If you have an older Lionel engine marked "command ready" it only needs the R2LC radio board to be added to give it TMCC functionality. Otherwise you will have to use a full upgrade kit such as those offered by ERR to convert your engine to command control, or the ps2 upgrade to give it DCS control.
I think others have adequately described the difficulties in making this work, but it can be done.
Edit: After reading the post made while I was typing up this too-long essay, it seems If I understand correctly, that you would have to reverse the wired to the motor on one of the engines, assuming they are both Lionchief, so that one will go forward and the other reverse when you turn the throttle on the LC remote. I'm unsure if it is as simple as that, But I think so.
Lionchief/+ locomotives will work on any brand of O-Gauge, 3 rail track, as will the offering from all the other product lines and brands in 3-rail O scale. The opinions on which track system to choose vary widely from person to person, as well as for what you intend to do with it. Some brands/types of track work better for temporary, floor/table top style layouts, and others are preferred for permeant layouts. You can find a lot more on this by searching the forums here for things like "which track should I use"
Brick, as used by folks around here usually means a Lionel brand, 180 Watt powerhouse, power supply. These are the transformer of choice for many folks running command controlled layouts with no need for conventional control. Unless it is an issue specifically related to 'bricks' versus some other transformer, the term will generally just mean whatever transformer you are using to power your layout.
Anyway, Hope this was somewhat helpful and didn't put anyone to sleep.
JGL