In answer to the various questions:
I have two Watsons and an Alden (I think) -- the Alden is made of bakelite and is beefier than the plastic Watson, although they have the same basic design. For cassettes, when I owned an M7 I bought a box of 100 the pre-DX coded (400) cassettes from Freestyle. I still use 'em along with miscellaneous cassettes picked up over the years.
I use 3/4 inch masking tape to load generally, but in a pinch have used cellophane (Scotch) tape.
I think Sitemistic's advice is sound regarding re-use of the cassettes. The felt light traps get schmutz in them (dust, grit) and can scratch film (which after all passes through the trap three times (loading, shooting, rewinding) per use). With careful cleaning (blower, followed by scotch tape) you can get more use out of them than five . . . but why risk it? Snap-cap cassettes are less robust than factory loaded and I have had them open when dropped the wrong way. I store loaded cassettes in the plastic containers from rolls of factory loaded film, so that if they are dropped, the plastic cannister takes the impact. When it matters (paying jobs, once-in-a-lifetime trips etc.) I tend to go with factory loaded film. But for casual use I must have used thousands of feet of bulk film since I started taking pictures twenty-five years ago -- mostly without incident.
As mentioned above, 100 foot rolls of Tri-X are easy to find, they just aren't exactly cheap any more. They can be frozen for a long, long time without degradation. I wouldn't bother freezing or refrigerating film though unless I was not going to use it before the expiration date or unless I lived in a hot, humid environment.
Loading the bulk loader with a fresh 100-foot roll must be done in the dark, obviously. If you load cassettes from start to finish in the light, the last two and half inches of film in the cassette (where you attached it with tape) will be fogged. If you can get good at the whole procedure in the dark, you'll be able to preserve these frames. Otherwise, my advice would be to "over load" by a couple of frames, trust your film counter, and stop at the 36th exposure.
One advantage that hasn't been touted above: you get to decide how many images will be on a roll of film. No more half-rolls of lens tests, followed by poorly composed snapshots of the cat. Or fewer, anyway. And if you load between 18-20 rolls of 36 exposure film , you're still looking at around US$2.50 per roll plus the cost of a re-usable cassette, which is not so bad after all.
For reasons that I won't get into, I recently started developing some film which is about a year and a half old -- and during the intervening time, I've really mostly shot digital. When the film was dry, spotted and scanned, I made some inkjet prints, and I've got to say that I love the look that a 400 speed film gives you right out of the camera. Just amazing.
Ben
