Good deal, but I think Deco and Eero are better. I went straight to a proper network and never used mesh, but I always read most issues with Orbi and Nest.
1sh0t1b33r
That won't do anything. Powerline is trash, but so are extenders. You'll have better luck with a mesh system, but you still have to mind the placement of the satellites so they are in good range of the main unit to relay the signal to where you need it. But the best will always be running an Ethernet cable.
Do you not have a router? If you connect modem to switch, I'm not sure how you are getting an IP unless it is sharing the one public IP you were given by the ISP. You should have modem > router > switch > PC.
You can't have multiple routers like that. If it's rentals, you'd really need to get and pay for your own ISP and then you can register your modem on the coax line. Otherwise you'd need to convince the huge house owner or whoever owns the ISP contract to invest in a better network, whether it's some kind of mesh system or a proper ceiling AP setup.
I don't know, but you can definitely enable 5G on your other AP. To limit interference, just set them to different channels. There are many more non-overlapping channels on 5G than 2.4G.
Not by a switch. You'd need a multi-WAN port router. Something like the ER605 will do failover.
20-40 isn't that bad. Since you are looking at 'gaming', assuming you are on Wifi. The best method is to wire your PC. Anything 'gaming' is all marketing to up the price.
With most ISP's, you only get 1 IP unless you have a business account. Plugging in a switch so you can run extra WAN connections to a router will not magically give you extra speed.
Hope that's a shielded cable, otherwise you may suffer from Cat to Cat interference.
Run a Cat6 cable, not whatever this is.
You can add a switch, but you cannot splice.
Is it a shitty cable?