1.) I have a Bernina 440 QE (without the emb unit, it was alot more and I didn't think I would ever use it and I probably would never have)
2.) Everything. It purrs like a kitten, when I first got it, I was amazed how it just seemed to sew so effortlessly, the fabric just slid in. I don't know how else to describe it and it still does it for me.
3.) The BSR, the many feet that are soooo easy to change. The new stitch in the ditch foot for the walking foot.
4.) I paid 2500 five years ago. It was a special sale that my dealer was running. They had a no interest program running through Bernina that I used.
I would look for a good used machine, try Craigslist, try all the dealers you can drive to, they all have used machines to sell that have been given the once over.
Good luck and remember, nothing sews like a Bernina, nothing.