For the initial issue of this post, I'd have to disagree with the opinions that HP5/Rodinal are not a good match. This combination suits me very well, especially for the Olympus 35RC that I keep loaded with HP5 as an "always on me" camera when on trips. My processing details are Rodinal (or RO9) at 1 + 50, 20 degs C, agitate for the first 30 secs then two inversions each 30 secs for a total of 15 mins. Usual stop, fix, wash, etc.. Though grain would undoubtedly show at higher enlargements, for my usual 10" x 7" it's not an issue at all. The tonal range and convenience of a fast film and a developer concentrate with a virtually unlimited shelf life have a lot going for them. My suggestion would be that you resolve the changing bag/light leak issue and persevere with that combination. Doing your film reel loading at night gets you half way to solving some of your problems.
Good luck with it!
Steve