Hi Vesly, me too i am a complete newbie about the assembly codes, but i would still try to help you solve your problem, maybe two can do it 
from what I understand, you are trying to recreate combat arts, uch as Echoes or TH3, right?
your first question was about it global flags
these bytes from what I have been able to understand from my previous experience are particular, because their state remains saved for the duration of a game, obviously if you create a new file
lifesaving systems start fake
in my project I used them to create multiple choices throughout the various chapters, to activate these bytes, you can easily do it through events, both of the event assembler (buildfile) and the editor of FEbuilderGBA as any other temporary flag
In this code in this code, the section that controls the byte (at least I think so) is:
CasualCheck: push {lr} mov r0, #0xb0 @unused permanent event id *this is the line with our byte* ldr r3,=0x8083da9 bl goto_r3 pop {pc}
because this code checks if the flag 0xB0, he is active to do anything else
> ldr r3,=0x8083da9
this string, I’m not sure it does, but I believe it calls a vanilla function
i think you can use this piece of code to check any other flag bytes
for the CSV tables question, some I think are extracted from the base game, while others are modifications of the latter uch as that of the magic of the characters.
but I don’t think you need it, also I think through the definitions you can change the values of these tables senda go and really touch them (m pretty sure about that because I’ve seen it done)
about point c, I didn’t understand, sorry 
while for point d, I did not know of a code for the combat arts but I’m afraid it’s not complete
Chapter 5 appendix by Sme
speaks of combat art as a function that could have come later … and for a temporal matter I think it has not been completed yet, we should ask the original author, it could probably help us
Finally about the final advice, I think we could create a kind of combat arts through command skills, we can try to see how the codes of abilities like capture and mercy are structured, if I’m not mistaken, the capture skill gives the user a debuff, we can lead it to be a buff instead and you can do, stupid example, make the user’s hp pay in order to use them, for this we must also create a function that sees that the HP of our character is greater than a certain tot, always if we do not want to make him make a suicide attack
don’t be afraid to use the buildfile if you also use FEbuilderGBA, I use them together, and never had any problems, to do this you need to use the Custom Skill Build sectio, it is not difficult to use, but if you have problems, I can try to help you
Maybe my message was not very helpful, but I hope that at least it gave you some advice, however I follow this new topic with interest, and if you need help, you can safely contact me, two minds are better than one is not? 
and forgive me for my english