If you shot on newer Canon DSLRs like the 1D and the 5D, you'd probably like the 1V the most. I'd get it over the 1N. I have a 1V and it's a fantastic camera. Without the battery grip, you can get about 25 rolls of film per battery, give or take a few rolls. I'd buy them in bulk on the internet to get the price down to about $3/battery. With the battery grip (PB-E2), you can get a lot more rolls and use all kinds of AAs. Though I don't think it likes rechargeables - too low voltage if I recall. I don't use my PB-E2 most of the time because it adds too much bulk for me. There is also a smaller grip (BP-E1?) with no second set of controls. It lets you power the camera off of a 2CR5 or 4 AAs. I found it was a bit harder to track down than the PB-E2, but it could be useful.
If you feel like switching to Nikon, the F6 looks like a great camera. Personally, since you are comfortable with Canon, get the 1V (if you are ok with the price - $500-600). It's the best film camera Canon will ever make. If you want a manual focus camera to back it up, pick up an older Nikon or Olympus or... But get the 1V
I've only shot a couple rolls of Provia 400X. It had pretty fine grain (for me) and was great stuff. Just a tad expensive. I should really shoot more of it. Good skin tones too. I'd say it was less grainy than something like Portra 400NC but probably more than Portra 160NC and definitely more than Ektar. It's not going to be as fine grained as a slower slide film, but it's ISO 400. It blows the doors off of Ektachrome 400. I don't have any samples of it up scanned at 4000 dpi, but I do have some that have been down sampled to 1800x1200. I could send you a crop of a 4000 dpi scan if you want...
Provia 400X