jess,
First running the trains (we'll get to switches and operating tracks later):
Because your collection is Postwar, and not Modern, you won't apparently be using any Modern command control locomotives, at least in the short term. If so, unless you want to buy a Modern-era transformer, you'll need at least one PowerMaster, which is a box that adjusts the track voltage in response to commands from a CAB-1 (or CAB-1L or CAB-2) remote control. You can think of it as a wireless "throttle" for running postwar engines from the remote, and using power from one of your old transformers with its handle set to full on.
If you're planning on multiple loops, meaning you expect to run more than one train at a time, you'll need one for each loop running a train; and then probably one more for the yard.
(The advantage of command control is that these PowerMasters are not needed, simply applying full voltage,18 VAC, to the track will do the job, because the "throttles" are already there, present inside the locomotives.)
There are several generations of PowerMasters, the newest being the Legacy PowerMaster series. It has two models: one can supply 180 Watts of power (6-37146, for standard trains, pulling all freight cars, or at most a handful of traditionally-lighted passenger cars), and a second that can provide 360 Watts (6-82883, for big locomotives pulling many such lighted passenger cars.)
Or, you can go back a generation to PowerMasters that are called TPC's. These are available in 300 (6-14189) or 400 Watt (6-14179).
My best suggestion is to let all of the above sink in before moving on to switches and operating tracks.
Mike
