Welcome!
Is the bombs-away site still around? I do remember downloading a few things via there recently.
As far as collisions and crashes, after flying what's probably a few dozen missions, I did the math to keep track of losses etc. and I realized that on average your chance of dying in a mission was a lot higher than in real life, and that the enemy fighter AI was unfortunately not that smart at avoiding crashes and often not good enough to be a threat, except as a kamikaze of sorts. I also found that flak is more deadly than it should be.
So as a compromise, I found that the most "realistic" if you want accurate results would be to turn plane collisions OFF (as much as that sometimes creates silly planes bouncing across the sky), turn the flak accuracy down to low or medium at most, and set enemy AI fighter difficulty to highest. With that, I found the game a lot more enjoyable and challenging and turning out with much more historical mission results. You always have 18 B-17s flying in that box formation in campaign missions (6 from your squadron, 12 from two others in your wing), and in the long term the average should be no more than 2 bombers lost per mission. If you're constantly losing much more than that, it's not really realistic.
As for bomb sighting, practice practice practice! The bombsight is actually extremely accurate, probably even more so than it was in real life. Numbers are important, but really the important thing is just to make little adjustments by feel as you're approaching the target and keep making them so that the target is as stable as you can get it in the sight, all the way till release. And remember the goal is not laser accuracy, you just need to be close enough. With a little bit of practice, the game's sight is forgiving enough that you'll learn to get that "close enough" pretty much 100% of the time.