We're using supplies from Born To Love, whose service has been consistently wonderful:
and the secret weapon for avoiding pins...
Snappys are three bucks apiece, but you only need a few and they work great.
As far as fitting goes, I think the only page I read on the subject was at BabyCenter.
For holding diapers, we have an empty ten-gallon grain bucket, which is just the perfect size to hold a Bummis Diaper Pail Bag, of which we have two. Dirty diapers go in the bag in the bucket. Poopy ones get rinsed in the toilet first; I find they come cleaner if I get 'em well wetted when they go in the bag. I don't worry too much about getting them clean ; I just swoosh 'em around and wring 'em out.
Diapers pile up in the pail overnight. In the morning, after I get done feeding livestock, I pull out the full bag and put the empty bag in. The full bag gets dumped into the washing machine, and the bag itself gets tossed in with the diapers. Our machine has a super cycle that is soak, wash, rinse, extra rinse. I wash them on this cycle with 1/4 cup Tide free and 1/4 cup washing soda. When it's done, I toss in about 1/4 cup vinegar and run them through another rinse. Then it's on to the dryer.
This is all so simple that I can't imagine why anyone would want to put toxic gunk next to their baby's bottom and then have "disposable" diapers to dispose of.