So the answers to your questions:
1. My house is about 30ft long and it's at one end on the top floor. It's three floors, and we dont have any "Dead" zones, although the signal is quite weak in the basement at the other end, but there will be an ap down there at some point so that's not a problem.
2. According to the Linksys Control Panel, we have about 15-20 devices running on average at the same time, with most of them being smartphones/tablets, and our system of Amazon Echo Dots.
3. My modem and router are currently located (Like I Said) On the top floor of my house at one end. We could move it, but then it would just be in the basement In about the same place.
4. Like I said, We're going to end up installing ap's at some point, but it'll probably just happen when we get a new router, or if we're bored someday. I'd prefer to just install ap's instead of buying a MESH system, but I'm open for any suggestions you guys can throw at me.
Also, would you consider WiGig (60ghz) a good investment or not, beings that only a few devices support it and it's SUPER short ranged? Would it be a good future-proofing measure?
-Thanks
(Btw sorry for not getting back to you for a few days I was out of town all weekend and didn't get a chance to check it)