I've been running DCC on a large (as in, the entire first floor of my house) layout for about five years now, so I can clarify a few things here.
For starters, the wireless 10 amp NCE system is available for $600 from places like Tony's Trains. The set includes everything you need except the power supply. I recommend this one, for $90, from mouser. It is small, fanless, and plenty powerful. So $700 to get going with a fully functional wireless 10 amp system.
You do not necessarily need multiple boosters. I run my entire layout with a single booster, and that's with plenty of engines running, pulling 20-30 car trains, powering all accessories, lights, etc. off the booster. I am typically running about 5 amps DCC output during a normal operating session. Multiple boosters are handy if you want to subdivide your layout (for example mainline vs, yard), so that a derailment in one section doesn't bring down another section, or for very large layouts. But the starter 10 amp booster will be more than adequate for most.
The NCE remote is very nicely laid out and easy to use. All the standard MTH PS3 functions - smoke, couplers, lights, all the sounds, etc. can be controlled via DCC. It's all quite well documented in the MTH manuals. Programming and setup is somewhat easier if you use JMRI along with the NCE, but it is not necessary.
The NCE system integrates nicely with JMRI for control and automation as well, so you have all the options imaginable as far as using tablets, smartphones, and touchscreen laptops for controlling the layout, automating routes, and other whiz-bang. I have JMRI set up with a full graphical representation of my layout that is controllable wirelessly via laptop and ipad. It's a lot of fun using the ipad in conjunction with the remote for heavy duty yard operations, etc. I think I have some posts somewhere about my JMRI setup.
Related rant: Smartphone/app/whatever control is simply not an option IMO as the primary control input for a system where real world hardware can be damaged if you lose control. I don't want to by typing in a passcode, waiting for my phone to update, closing out whatever popup is up at the moment, etc. while a train is running off the track. There's a reason nobody operates industrial machinery like cranes with a smartphone...
