If it's already threaded for a flash suppressor, you simply put on a washer (crush or peel washer), then you screw on the flash suppressor. If it's not threaded, then you need to have it threaded.. although this can done with a simple die set, I'd recommend you leave it to a gunsmith.
Into the left side of the receiver.
1/2 28
Depends on the rifle- some do not HAVE a bolt catch. On the AR15 family of rifles, it is the left side of the receiver.
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.
You will need a free-float hand guard kit. These can be purchased online. Check out this video for an example of how to install such a kit: http://www.wonderhowto.com/how-to/video/how-to-install-a-free-float-handguard-on-an-ar-15-rifle-267096/view/
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
By it's serial number. Go to www.proofhouse.com and under 'long rifles' listing look for AR15 Sporter
Depends on model.