OK when I soak off I usually take a cotton pad (lintfree) soak in acetone, put onto nail, wrap in tin foil. Do this for each finger, wait about 10 minutes and start taking em off in the order you put them on. if you pull one off and its not really soft, put it back on and continue soaking it to soften it.
Nailbiters: I don't like tips full stop, so I wouldn't use them on a nailbiter unless I used a clear tip. Again, I'd rather sculpt and extend the nailbed with a custom blend of pink coverage (I use EZ Flow and have mixed up a couple of coverage pinks for this purpose, one warm, one cool and one neutral - based on the HD coverage pink - wouldn't use the coverage pink alone as it looks plastic to me).
Anyway, there is a tutorial on here about how to give nailbiters a nail without using a form. Do a search in the box and you'll find it. Basically you put product directly onto the nailbed to extend it. As a one off, its fine, but if you have a nailbiter who continues to bite the enhancement off after you've done this, well its not good to put product directly on the skin in a constant manner (overexposure) but as I said, as a one off, should be fine.
Good Luck & HTH's
Nancy