There might be a way but I wouldn't be able to do it without a gamesave that has all of that unlocked.
As for Infinite HP I have been doing a lot of testing today and I think I have a much better understanding of how it works. Unlike what I thought with my previous codes HP values and addresses are not uniquely tied to the characters themselves but which character is active, and which is not. (this is why it got weird for me when I didn't have a second character).
Resident Evil Zero ver. 1.0.0
[Infinite HP - Primary Character]
580F0000 012ACB50
780F0000 00001380
640F0000 00000000 000000FA
This means if your offhand character needs to heal you can just switch to that character and they will now have the value specified by the cheat. Finding a stable value for the offhand character has been pretty difficult because there are a lot of variables involved (Rebecca has less max HP than Billy) and testing HP for characters you are not controlling is a bit of a pain. Unless it's hugely important, like if your offhand character likes to get themselves killed often, Im not really sure it's worth the effort. This code should be pretty solid.