You got the wrong info, or you are interpretting it wrong. With fingers you may need a bow with a 28" draw. If you choose a bbow for release shooting it should be approx. 1" shorter than one for finger shooting. That doesn't mean that you'll draw the bow to a different length. It's just that the string wrapping around a few fat fingers has to be longer than the string wrapping around a release head. There's a bigger radius with fingers. You undertsand what I'm trying to explain?
Second question. You can usually shoot an arrow an inch shoter than your draw because the rest is set back on the riser. Depending on what rest you may find you can shoot even 2" shorter. Just don't go ordering things that way though. Wait till you have the bow setup for draw and let the pro-shop help you out with arrow length.
Number 3. Yes some bows allow a lot of adjustment. I shoot Pearson and most of their bows can be adjusted from about 24" to 30 or 31" by just changing a module. Other companies can do likewise, or use a different method of adjustment but I can't say which ones or how.
These are all good questions and the ones you should ask at a shop before you buy a bow. Whatever you choose be sure that the draw is set up right, and if you err do it on the short side. Use your shop, be couteous, but become informed by asking questions. Good luck