I don't recall when I started some of my behaviors, but others go way back in time. When I was younger, grade school years, I pulled my hair. Thoughts of suicide have never been very prevalent in my mind. They seem to occur in cycles, at least the one for eyelashes. I'm currently in one now, and if an answer isn't found, it will occur in another six months or so.
Hair pulling is called trichotilomania, and can be treated with a number of medications.
Likewise, the nail biting can be treated with the same medications. There is a trichotilomania foundation in California, and they have a website to query for referrals for treatment. That is your best bet.