To Ken yes, development does continue in the water stop bath, more so in the thinner areas (shadows) and less so in the heavier areas (high values). But to really notice a difference you would have to go back and forth from developer to water stop a few times.

Will my development method work well with Pyrocat?
What is a good starting time for development ( I normally work at EI 50 on the film)?
What type of agitation cycle is recommended?
What stop times and fix times are best?

Any other tips or recommendatons in the processing?
FP4 and Pyrocat-HD is an excellent combo. I have uses both 4x5 and 8x10 formats. Pyrocat is also a great developer for Stand and Semi-stand development if you want to see extreme edge effects.
For normal processing in a tube or tray, EI 64. My times are a bit longer than the norm for Alt processes, anywhere from 10:30 to 14:00. For silver printing, 10:30 (tube development), 11:30 for normal development in a tray (agitation 5 sec every minute). For Stand development, EI 40. 1 minute constant agitation at the beginning, 10 sec at 30 minute mark, and that's it. I do Stand development in a tube. There is a lot of what appears to be bromide drag, so to reduce this effect I pull the film out of the tube and invert it. Stand development is trickier than Semi-stand.
Semi-stand is in a tray. 1 minute constant agitation at the beginning, then 5 sec every 10 minutes. If I let the film rest for 15 minutes instead of 10, I get lots of developer lines.
I dilute Pyrocat 2+2+100 for normal processing (not stand), and for Stand, 5ml+5ml+1200ml water. I use a citric acid stop bath (30sec) and Ilford's Rapid Fix (5min).
21 C for all processing.
Some people give a water bath before development, but I don't bother with that.