I've kept an exposed roll of Pan F+ 120 for about six weeks before developing with no problem at all. I develop Pan F+ in Diafine. It does tend to build contrast quickly and the speed is suited for bright lighting which tends to be contrasty. Diafine handles this well and gets an effective extra 1/3 - 2/3s stop out of it. I mostly shoot this combo at EI 64.
FP4+ is a great film. Other than a shorter toe, which won't matter if you don't expose shadow detail on the toe, you won't notice that much different about it from Plus-X. It's my go-to medium speed film, especially in 120, but then I seldom shoot 35mm black and white anymore since getting a couple of medium format cameras unless I really need speed, and even then I have f/2.8 for my Mamiya and Delta 3200 at 3200. But I do like FP4+ a lot in 120.
Oh yeah, I load bulk loads (got a 100' roll of the Arista branded Tri-X when it was way cheaper than now) in plastic because that's what I've used for years. Years ago I had metal film cartridges pop open when dropped and have light leaks, and I don't get either, so far, with plastic. But consider carefully the actual savings. I just don't find bulk loading to be worth it any more.