1. Eizo monitors are best, but are big bucks. Get Apple/Dell ones if Eizo are out of your budget. The bigger the better. Nothing shits me more than a small screen when working with photos (23-24" (1920x1200 res) is what I'd recommend)
2. You need a hardware calibrator. They vary in price, but the most popular one is the
ColorVision Spyder range. The key is to calibrate all your devices the same (camera, computer, printer).
3. RAM is important. More RAM the better. Macs are always good, but on PC there is Adobe Lightroom, which is a pretty sweet app. So if you're on a tight budget and can't afford new Macs, get more RAM (at least 2GB, 4GB is great).
4. Stylist? I think you mean a graphics tablet? If so, Wacom. Nothing but Wacom.
5. For photography, probably not.
Also think about backups. If these photos are important, off-site backup may be useful (this could be something like uploading to something like Amazon S3 or a server elsewhere via the Internet).
If you've got any more questions, fire away
