It is fair to say that most of the "mainstream" regionals that you may be hired at all work under a min guarantee somewhere near 75 hours. You will be paid 75 X (pay rate) every month regardless of whether you fly or not. Depending on how your airline is staffed you can make more money on reserve than you would holding a line. It was not uncommon here for a while that on reserve you could see excess of 100 hours credit. The safe bet is that you only count on 75 hours.

Getting off reserve is strictly seniority plus or minus a few numbers. Some of the senior folks may bid reserve "call me last" in an effort to sit home all month while getting paid. That frees up one line for the next junior guy to get. The general rule however is that all the junior pilots in base will be on reserve.