It really depends, usually at least 3--9 months, there are cases take 1--2 years.

DefinitelyYES.
My condo unit is 1050 sqft and I'm using bridging mode via LAN cable with 2 routers in order to maximize my 500 mbps package.
Else with single router, the opposite corner to your router will have bad connection (depending on number of walls in between).

I'm not a network expert, please try it yourself.
Important is to consider the signal have to passthrough how many wall in between and type of wall (behind the structural column that containing steel may no be a good idea).