Mike:
If you can keep your electrical load under 5 amps, you should be able to wire your layout in one section. 5 amps should be about 10 modern locos running at the same time.
However, you can;t rely on the rails to carry the current, especially through switches. Plan to run some thick wires under the layout to carry the main DCC load. Wire from this bus to the tracks at regular intervals, using a lighter wire. You have to wire to all parallel tracks.
You should add jumpers beyond any switches. Electrofrog switches will need the usual gaps beyond the frog to preven shorts, and then more jumpers. I don't think you can get any sort of reverse loop in 30", but these need extra wiring and a black box.
If you go for a walkaround control, you will need extra wiring for this. Usually telephone wires will do for this, but see the instructions. The Lenz system I worked with had telephone jacks or RJ45 every so often around the layout so you could follow the trains. If you are going to do major shunting or switching, you need a socket or two for each yard.