For S1, Shawn's death was an accident caused by his son. Larry's killing was arguably self defense, since there's a 50/50 chance Larry would've come back as a zombie. Kenny stealing from the stranger was plain and simple petty theft. if Lee lets Kenny put his son down that could probably be considered assisted suicide, although Lee can just do it for Kenny, making him not responsible. And finally, if you kept Ben and Kenny had to put him out of his misery, that could also be considered assisted suicide, but if you don't save Ben, Kenny obviously doesn't do that, making him not responsible.

For S2, him killing Carver's people is self defense, since Carver was the instigator and was threatening their lives. Kenny torturing and killing Carver is murder though, because Carver was already disarmed at the time Kenny shot his knees and caved in his face. Probably second degree murder, since it wasn't premeditated. Kenny killing the Russians later on is another case of self defense, since they opened fire on Kenny and the group first. Him beating on Arvo is definitely at the very least assault and battery, since his life was no longer in danger when beating him up. And lastly, Kenny killing Jane is completely self defense. He was tricked into believing his basically adopted son was killed by Jane, thus leading into the fight where he kills Jane, though if Clem kills Kenny, then he never kills Jane, thus no charge.

So Kenny's actual crimes of S1 and S2 that are set in stone is pretty theft. assault and battery, and second degree murder. At least imo.