GGxx AC+r potemkin troubles

Recently ive been trying to play potekmin and its been going ok however there's 2 main issues im having that are holding me back at the moment, which i wondered if anybody can help me with, in no particular order

1. Hammerfall Frc, namely does this thing have variable timings when done at different distances? because sometimes it feels like it and also picking up with 5k 2B heatknuckle seems really odd and strange with wildly different results, sometimes i'll frc and i can't even connect the 5k, obviously this might be a gravity issue/character i'm not paying attention to as in "it might not work on so and so" which i get that's on me, or is the timing just that tight, because even sometimes when substitute 5p for 5k i still mess it up

2. Aerial potemkin buster in combos, So i've watched i think frankentanks potemkin bnb guide which was very helpful, however this part left me quite confused and i'd just like some clarification on a couple of points

"try time your rotation so you jump backwards" So this is because i want the APB to come down forwards or in place?

If this is a yes, then id like to know why i cannot just do a standing 360 which 100% of the time always jumps back anyway, which ive tried and 100% never works

Now watching closer im able to figure out that he actually uses faultless defense which ive tried and ive managed to get to work a couple of times, but when i do hammerfall break FD 360 i usually always jump straight up or completely whiff the throw

So am i just doing it too slow? too fast? what sort of frame window am i look at between hammerfall break and FD 360 APB

Thanks for taking the time to read, hopefully somebody out there can give a brother a hand