Sounds like you've determined to get 19" wheels, but I hope you also realize the diameter + reduced aspect ration will mean a much higher chance of rim damage down the road. Hitting a pothole, curb or speed bump can easily bend a rim, so get to know your local wheel repair shop.
As for your last few questions, scraping is bound to happen on occasions, even with NO drop. It really depends on what size tire you go with. Do you have a chance to test fit these wheels before you purchase? It's really the only way to know about critical factors like brake clearance and whether they stick out beyond the wheel wells.