@SO-Net-2020 

Query 1: You do not connect an Ethernet cable from one powerline to another powerline, they communicate using the electrical outlet. So you would have one TL-PA8010P connected near the router, and an Ethernet cable from the router to the adapter. Then you would place the two remaining 8010s and 8630P where you want them, assuming they will be able to see each other via the electrical wiring. 

Query 2: You can add the 7020s to your network so the PA8010 wired to the router will provide internet to every other powerline node. 

@SO-Net-2020 "WPA8630P near the router with three LAN cables going into it"

Actually that model has 3 lan ports in it so that when it is the one in the other room from the router then you can plug in 3 computers. Plugging 3 cables from the router won't do any good at all. It will probably confuse it, actually.

So use a network cable from the router to one of the units with only one port. Then use the 3-port model in another room where you might need more than one computer or device (TV, etc).

As for seperating the networks this is best done with network settings if you need to enforce security. Powerline units try to all sync with each other and it is hard to keep them from doing that.