KICKER - CompQ 12" Dual-Voice-Coil 4-Ohm Subwoofer - Black

They are 850 watts rms & 1700 watts max

I got 2 12's and i need a battery big 3 is always a good thing i got the 46cxa1200.1 on them now need o gauge for the 46cxa1800.1 they r 850 rms and a good strong box recommended

The 1800 watt one would be a better choice. The 1200 would work but they would be underpowered since it would only put out 2400 watts max & they are 850 watts rms individually (1700 watts max) & could handle 1000 more watts than that amp could put out. The 1800 would put out 3600 watts max, which is 200 more watts than they could handle between the two of them but as long as you didn't crank it up all the way & keep it that way for long, that wouldn't be a problem.

Probably not. They're close to a foot tall on their own with no enclosure. Your best bet would be "shallow" subwoofers in a shallow box.