Don't confuse the Betty crashing after a bombing run with some kind of error in its flight path. The stock game Betty is a bit less protected than the other planes (they didn't call it the "Lit Cigar" for nothing!), it will crash more easily than other planes due to having this factored in. It has less armor, less damage hit point requirements than other planes....and rightfully so. Just a few hits from AA fire and it's going down.
As far has the planes "loadout", it can carry about anything you want. The trick is to have a specific plane setup to carry that specific payload.
The planes "ClassType" defines what kind of function you expect it to do....Torpedo bomber, Dive bomber, Straight Line conventional bomber etc. You then define its "loadout" with the proper placement of the position of the bomb(s) in its .dat file, then make sure their listed in the planes .cfg files. I've found if you want a plane to do a specific type of run, you need to make it specific only for that type of technique. Having a Torpedo in the planes loadout along with two 500 lbs bombs only makes the game scratch its head in wondering which load should I use?
I just finished reworking the stock game Kate bomber to make it exclusively carry, and follow, a Torpedo bomb run. The stock game has it carrying a couple of 250 lbs bombs
and a torpedo on occasion. The trouble is, the plane will usually carry the 250's before it carry's the torpedo. We seldom see a torpedo run in-game from the Japanese side due to this. Fotrs Ultimate now has a Kate that skims the water as it approach's and deliveries a death hit from a torpedo to a sub if you let it!!