Extended Wifi

I have an ASUS router with 4 external antennas. I am guessing two for 2.4 ghz band and two for 5 ghz band. I am about to begin running CAT6 throughout my house for hardline connections running off a switch. My question is this:

If I remove the antennas from the router and connect with an LMR240 cable and extend them roughly 30' away to sit over areas of my house where people tend to congregate with wireless devices...phones tablets...would it be more beneficial than say, just adding a second router on the opposite end of my house? Are the antennas intended as a transmit and recieve or possibly a diversity and main? If the latter, is there anyway to determine diversity andmain? My point being, if I can split two channels and place the antennas at intervals in my attic that would cause the RF field to bisect and "blanket" my house rathet a centralized router location pushing out in a specific radius from center.

I know :TLDR: , just trying to think in normal RF patterns and coverage.