Not sure if this would work for you, everyone's different, but I gave up wearing underwear most days when I got to this stage. It really was much more comfortable that way, and saves your laundry problem. :-)

Nursing bras - if I did this again I wouldn't buy more than one now, really, since there can still be quite a variation in size afterwards. The books etc do say that you can gauge from your size now but honestly, you can't be sure. Find a style/price you like now, and go/send someone to Mothercare (or wherever) on day 8 or thereabouts, when things are starting to settle and you can make a slightly more accurate measurement.

Good luck.