Xtol is normally replenished as stock solution, rather than 1:1, and the common rate is 70 ml per 120 or 135-36 (shorter 135 rolls use proportionally less).
For "flushing accelerator" I presume you mean rapid fixer; I'm not familiar with replenishing fixers for B&W, but you can safely and effectively use C-41 fixer and follow its replenishment rates.
For Photo-Flo, again I'm unfamiliar with replenishment. Photo-Flo doesn't have anti-fungal agents as C-41 Final Rinse does, so it will have a fairly short tank life even if you can replenish it. I'd suggest you may want/need to mix it fresh each day.