You can run lots of ethernet cables without a problem it doesn’t dilute the existing outputs you can even add something called an ethernet switch to add more. They do external wifi access points you can stick on a pole outside to cover an area. It’s best for speed to run those off an ethernet cable. You can power them through the same ethernet cable as well to simplify installation cabling. Its only when you want to run very long cables +300mtrs you might need alternatives.

It should all work as is. I’d hook up a router to it and see. You can upgrade the switches at the bottom at your leisure if you need to. But if you just moved in you probably have 1001 other things to buy. 100mb switching is probably faster than your isp connection anyway.

Fibre is infinitely more able to expand speeds than wifi. Remote Rural areas will eventually catch up as the prices drop in time.