1. Depends on the condition of the specimen and the care its given. If you get a healthy specimen, and give it the care required to start feeding (better yet purchase one thats already feeding), they're great fish!
2. They're angels. :lol: In other words, yeah 50/50, but it also depend s on the animals you keep with them. Most SPS should be OK, maybe the occassional nip. LPS, softies, etc. is probably fair game. Keep them well fed, and again you'll have btter success keeping them with coral.
I suggest setting up a little QT (if you dont have one) and get him healthy and feeding, then toss a frag in there and see how he reacts. Of course thats not a 100% indicator of what he'll do in your reef, and for the most part when angels go nuts, its after they've been model citiznes and been in the tank for a period of time.
If you dont want to have to worry about catching a little guy out of a 150 gal if necessary, or dont want any of your coral touched ever, dont get an angel. On another note, I've had better luck with angels being "reef-safe" than with tangs.