well for the biting i tried ';No Bite'; from wal mart.
its just a like a clear polish and it tastes so awful you will put your fingers to your mouth and it will remind you not to bite your nails and eventually you will stop. it took me about 4 months of use and then i just didnt bite my nails anymore.How to quit Nail and Cuticle biting.?
Perhaps wearing gloves might help.