If you are planning on using Channel Plus they will design the system based on your needs. That is assuming of course that you can provide them with specific information
such as signal type, signal strength, length of runs, etc.
Since as you said you are using existing wires I would hook up at the maun drop and see what I got then work my way forward adding if and when I need to.
As Daniel suggests though make sure to use good quality distribution, makes for a much easier time!
Good Luck!