Sure, they can be added - it's not particularly difficult, but if your not comforatble doing it, a gunsmith should be able to help you out (I don't know for sure, but it doesn't seem like something that would take big $$'s).

I don't know of any options that aren't going to require hole(s). There is a barrel mount option for the front swivel, but you would still need a mount at the butt.

Check out Brownell's @ www.brownells.com (I think) - they have slings, swivels, mounts, etc...