well, it's a personal preference thing then, 1.5 inch is a lot consider where the jacket is now. Wouldn't the jacket be almost the same length as your sleeve (you can do a quick measurement), even BBBF is not that short. I don't think it will look good, if you really want to cut it, then perhaps 0.5 inch?
That is a good point you mention, like you I would prefer the jacket to be at least a bit longer than the sleeve. If I take the sleeve up 0.5" I think it is possible to take the jacket up another inch. I may have it tailored instead if it is an easy fix.
Vests and belts are kind of tricky. Remember the basic function of a vest is to cover your trouser-holder-uppers - but when vests were actually invented and commonly worn, your trouser-holder-uppers were suspenders, not a belt. There really isn't a 'correct' fit for a vest in relation to a belt, because vests weren't really designed to be worn with belts; if they were, they wouldn't have that notch.
Now that you mention it, I think I should really try a pair of suspenders or go beltless...