We have to remember that you are upgrading from a old ZX so you should be getting a complete new system include a cabinet, a new computer board (PCB) that has the latest revision and an antenna.
You will also need to have a RS485 cable (it is 4 wire cable) that will hook up between the pump and the new control board.
You will have relays in it which one will power the pump, another for spa light and another for pool light.
I think you were considering adding more pool lights - if they are connected to 1 relay then they will all work together - on, off, same color,
If you wish to have separate control then you will need the additional relays - RS-6 or RS-8.
Also, do you have a blower for the spa jets - if so that is another relay needed for that.
I know this is a lot to take in But better to ask questions now before it is installed.