Tell her to come and join us on the d'ya threads.
bfeeding - the rugby hold like hm said, with tons and tons of pillows. V shaped pillows are a great investment, for sleeping during later pregnancy, then for resting babies on while feeding. Grow a nice thick skin to ignore all the comments about how it is 'impossible to feed two'.
best buggy - jane powertwin if she drives a lot, nipper if she walks a lot.
For babies, jsut tons of the basics, because you get through so many sheets, sleepsuits, cardigans, socks with newborns, and you don't always manage to stay on top of the laundry. Forget 'proper' clothes, you won't have time or inclination.
Forget anything like cribs, or huge great high chairs with bells and whistles on, or changing tables - you need compact stuff and as little as possible when you have to fit two of everything in. You won't want to keep on traispsing off to a bedroom for changes 24 times a day neither!
Cook loads in the weeks beforehand to freeze for the early weeks. Arrange delivery of meals from any friends who want to help. Stock up on good books to read while stuck on the sofa feeding. A thermos for tea on standby since can't get up and walk around like when feeding singles.
Make the most of the pregnancy and last few weeks pretwins. Go out as much as possible and get lots of rest while at home!