With all three of these things I have managed to add persistent wounds (although in about 10% of my trials the damage was undone and the wound removed, but that may have been because the wound healed, or there is another check somewhere that I am unaware of for certain wounds).
Silly question, but did you check the has_breaks under flags2?
I ask because I've done basically the reverse of what you're talking about and until I flip the non-body flags I either keep flashing the wounded tile indicator, can't hold things, or can't stand up (even if you lose a limb and revert the wound totally, until you put stance/grasp count back to 2 you don't get the use returned), oh and the vision/breathing flags, but I forget if those are flags2 or flags3.
So it seems adding wounds to units is at least possible, now the issue is getting correct values for everything. I could definitely use some help in that department. What would be awesome is if anytime you are playing and one of your units gets a cool wound you could post all the values. Or if you have a fort that has lived through a bunch of different sieges and monster attacks I can go through the units (both alive and dead) and get a set of wounds, ranging from stubbed toes to torn in half. My hope is to build a, sort of, wound database, that I can use in modding and scripts to simulate an adventuring system inside of fortress mode.
I'll grab screenshots next time I get a cool wound worth keeping and try to preserve the values for ya, I did that with facial hair recently since my old urist mclegendary save was before I knew you could add beards to dorfgirls so world-gen dorfgirls lack them. I found out mclegendary got married shortly before I actually grabbed him for adventuring and decided to include his wife in the adventure but she lacked a beard. A rather kludgey way to do it is to simply scramble the style/lengths by changing the race in gm-editor, when you unpause (fort mode) or move/step time forward (adventure mode) you revert to your original race with your hair styles within normal ranges for your civ.
I was trying to figure out more about how to tweak the parts specifically and did some comparing with the males around her, ended up putting together a little cheatsheet with the values:
very short neatly combed sideburns
very long double braided moustache
very long neatly combed beard
long double braided hair
tissue_style tissue_style_id tissue_style_type tissue_length
1 2 39 150
1 2 39 150
2 0 37 156
2 1 38 246
-1 -1 -1 -300000
-1 -1 -1 -300000
2 3 36 137
2 3 36 137
-1 -1 -1 -300000
-1 -1 -1 -300000
-1 -1 -1 -300000
-1 -1 -1 -300000
Tissue style and style type don't change for dorfs from the same civ, looks like the first two values are sideburns, third is moustache, fourth is beard, five and six are always -1/-30000 (though these are 1 and 2 for beardless dorf girls, while the last four are missing entirely, body hair maybe?), then seven and eight are hair, with the tissue style and length parts under their respective headings.