should flash freeze be absolute zero since we see it turn dire into ice, not just incase him in it
DIO freezes people solid by drawing all the heat from their body due to his vaporization, as he says himself, when he vaporizes all the moisture in his body, it draws the heat out from the things he's contacting while he does, draing the heat from them, it's not AZ, he's just drawing out the heat to a point they become solid ice, that doesn't require AZ, though it is quite impressive.
should diavolo get minor darkness manip because of how he can stay veiled In shadow despite being out in the open
That's just him being hidden in shadows and artistic liberty, initially, every time we see Diavolo he's in darkness and dark places, kinda like Shadow DIO, who we don't see his face because of him always being hidden in darkness and artistic liberty. Stealth Mastery may work but idk, I'm fine with the latter if others think its ok.
does summoning your stand count as astral projection
I wouldn't really qualify it as such, it's only astral projection in the vaguest sense of the term.
should diavolo get resistance to fate manipulation with time erasure since if im remembering correctly one of the main parts of the stand is that diavolo escapes fate and can do whatever he wants instead of what he was fated to do
What he's doing falls under his existing causality manip, though
he isn't manipulating fate, he's ignoring it for those few seconds. So really, he isn't manipulating anything, it's more of an extremely minor resistance gotten via abusing cause and effect.
should there be a stand phisology page
Maybe, I think Strym wanted to do something like that.
and should stand users get resistance to soul manip since they tank attacks to their stand
Unsure. Technically they aren't resisting anything, their Stands are just durable enough to tank hits from characters that just so happen can interact with souls and ghosts and the like. And given whenever there is soul hax, unless your name is like, Novel Kars, it works just fine, like with Whitesnake's discs, Chariot's planetary soulhax, D'Arby hax, etc.
the limited Self-Sustenance should apply to all Hamon Users
Wasn't sure if we agreed on all Hamon users should get it. If that was what people thought tho, I can add it to the notable Hamon users, at the very least a "Likely [ability]". And explain it should apply as it seemed to happen automatically to Joseph, who didn't know why it was happening but it did none the less.