>>3428035You can get 30 rolls out of a C41 kit pretty easily, I just retired the stuff I mixed a year ago. Keep it in a closet in tight bottles and you'll be fine.
No experience with E6, from what I hear the kit won't last as long and you'll get fewer exposures from each.
B/W is a joke, just stand dev with Rodinal and wake up laughing.
I'm a proponent of DSLR scanning, but there are arguments to be made for the other options as well. If you're willing to fuck with your setup (pic related until I find a cheap copy stand / enlarger to use)and get it right, you can surpass all but a good drum scanner in quality and speed.