To Q1: It depends on the State where you are applying. Some states will give you a driver's license with a passport, others (and that is mostly the case now) require official US immigration papers. Call the local DMV to find out.
Q2: Your interview will be scheduled nearest to your location, or whatever the field office is for that location. You thus cannot pick the location, unless the 2 offices are equidistant to your location.
Q3. Yes you can; b/c immigration laws and particularly asylum laws can be especially complex, its best to contact an attorney.
If there are any questions on this, please contact my office