Yes diluted XTol is one shot.

Water stop is fine. Real stop is just faster at stopping development. I use a real stop first then a 30 second rinse to protect my fix. You could do a two bath stop with water for the same effect.

I test the fix before each session with left over 35mm leaders. You're looking for the time to clear the film. If it clears in under a minute I reuse the fix. Clearing time x 2 is the minimum fix time. Some films like TMax and Delta need more time to help get rid of color tint, extra final rinse helps too.

For all the modern films I have played with the hypo clear step isn't required. Hypo clear's sole purpose in today's world seems to be for use with fiber based paper.