Additional answers

5. I have used the same SSIDs (Netgear for 2.4G and Netgear-5G for 5G) for both routers and have never had problems. It may be better to use different names for different bands and routers, but I am too lazy.
6, 7, 8 I used configuration in 5. All IP assignment is controlled by the main router, and signals are directed to IP address so it does not have anything to do with 2.4 or 5g bands.

I have two wireless printers all configured using 2.4G hidden in different corners of my house. All my computers (7 of them) can access these printers.