I've had my Sundance Altimar for over a month now and I love it!
1. I have been using the Brilliance bromine system. (which was recommended by my dealer) I was originally interested in using the Nature 2 system (Sundance's SunPurity) after all the comments I was reading on this board as I have very sensitive skin, but my dealer said I should try the Brilliance first and if I wasn't happy with it I could try the Nature 2 ( He even gave me both in my start up chem kit.) It took me 2 weeks to really get it balanced correctly where I didn't feel I needed to rinse off right away. So far the water has been crystel clear and my skin feels great. I use the Brilliance system test strips as well and they're easy for a "novice" like me to read. I keep a written log too to help me remember what the reading are and what chemicals I add etc.
One Note: I haven't had a lot of people in the spa - just myself really and an occasional friend
2. I've just purchased my chemicals through my dealer. I have noticed eBay does have some good prices, but while I'm still learning I'll stick to the dealer...I've been using the Lavendar aromatherapy beads from Sundance that I got in my start-up kit. I agree with the others that the aromatherapy scent is not that stong - it really dissapates quickly!
I'll probably try other beads...
3. I don't have a vac but I did get a little "Grit Getter" which works on the turkey baster principle to suck up small particles. My tub is under a covered patio and away from trees so it doesn't get a lot of debris in it. I can see a vac might be helpful if you have a lot of people coming in and out or you have trees overhead...
Good luck - you are going to love your tub! Sundance Rocks!