If you wait till he defecates, it could be a while! I have some that only go once a month! As a general rule, 48 hours after feeding it is considered safe to handle your BP. There is no general guideline for amount/duration of handling. Just be aware of your BP's preferences. If he hisses at you, it's a hint! I handle mine 2-4 times a week, anywhere from 10 minutes to an hour, depending on the snake (I have 7 BP's).
My 3 footers usually eat a small to medium sized rat once every 2 weeks or so. Rule of thumb is one prey item as large as or slightly larger than the biggest part of the snake. If your BP isn't ready for another meal, he won't eat, so don't worry about overfeeding him.
Sometimes I vary prey size, just because they are opportunists in the wild, and don't always get the same size food. (Besides, it is fun to watch them eat something one and a half times their size!)
Can't help you much on your bite question. The only time I have been bit was by a juvenile, and she only got me with one tooth. If you've never seen a BP's teeth, they are like needles. It felt like a pinprick. Look at the pic in InvaderToast's photo gallery, you can see BP teeth. Oh, yeah. If you want a gallery, send me, BallKingdom, or Jeanne a Private Message. We'll hook you up with your own photo gallery.

Keep askin' those questions, it's a good way to learn!