I'm no expert (my oldest is 21 months old and my second is only 6 weeks old, so I'm just getting started), but I can tell you right now that a carrier such as a Beco or Baby Bjorn is a MUST. Everything is so much easier when you can just pop the tiny baby in the carrier and chase after the older child with your hands free. Baby will be happy because she is being held, and your elder child will be happy because you're involved in her life.
Also, if you have any changes you want to make, do it NOW. We moved our son into his new bedroom several months before our daughter was born, and he does not associate her with losing his room at all. It was very smooth! However, we did NOT wean him off of the paci before she came along, and I wish we had, because now she takes a paci and he sees her with hers and throws a fit every single day (because he only gets his at nap and night). I wish we had just had done with it before she came!
And the other moms are right, let the house go or even pay someone else to clean it for the first 6 weeks. Lord knows you're not going to have the time and energy for it! ^_^ You're going to be exhausted, but it isn't as bad (yet, at least!) as everyone warned me it could be. Good luck!