I would have to say no on the contact cement to attach the rocks. Most people (as I did) use silicone. It works pretty well but it is a bit messy. Don't buy the stuff from the LFS
though. Go to your hardware store and get 100% silicone. Don't get any of the stuff with mildew resistant or anything like that. Make sure it has 100% on the bottle. You get way more for way less money.
As for the ABS i'm not sure. I wouldn't see why not but someone else with more experience is gonna have to answer that one for ya.
Good luck with your creation.