|For a diaper pail, you can use anything that has a tight-fitting lid. While my normal diaper pails were being moved (I use several smaller pails, which worked well for my tiny-doored UK front-loader), I used one of those big kitty-litter tubs and it worked great. Some people use storage tubs, others garbage cans. Be creative and you might not even have to buy anything extra. When visiting my in-laws I just use a big paint tub with a heavy towel over the top (this works with a dry pail, but for safety reasons you wouldn't do this with a wet pail) and odor has never been an issue.
I have personally used the OS from 6.5 lbs on my scrawnie premie, and they worked great. No leaks, and I honestly didn't feel that they looked that huge. But how they look (and how you feel about how they look) can vary depending on baby's build and your bulk tolerance (for instance, I thought the OS looked bulker on my super-chunky DS#1 than they did on scrawny DS#2, but that's also likely because #1 was already straining the limits of clothes, while #2 had plenty of room). The OS will absolutely perform at the lower weights, but the S Sandys will offer a bit trimmer of a look for the very early days. Both are fantastic diapers. I use mostly OS (about 18 or 19 these days, I think), but have had about 6 or 7 Sandys to complement my stash. Having a few smalls can be nice for a slightly trimmer look before you can stop folding the OS, and I use the L now for nighttime, as they are slightly more absorbant than the OS (but L are also slightly bulkier than the OS once it's no longer folded over). If you do decide you want to mix things up a bit, I believe that ME will do mixtures inside of packages (wish I known that when I ordered mine), but you do have to call about that. Their customer service is awesome.