Colt - would be your best bet if you want a name brand - and something reliable.
pof-USA hands down
From 2013-2015 it has been the AR15.
Try AR15.com Try AR15.com
If it is one of the recent Colt .22LR AR15 rifles, then the answer is no - they are completely different internally.
1959
Yes
The US Army presently uses the M4 carbine, a shorter and much modified version of the Armalite AR15.
Colt has not offered a AR15 in 308
the brand "swag" is the best out there
The best brand of paintballs are Marballizers.
By it's serial number. Go to www.proofhouse.com and under 'long rifles' listing look for AR15 Sporter
The best brand is often a personal choice. Many people consider the Lenox brand to be the best.