The figures for the rules question:
V Deadshot (mine) on third click
E Gorilla Grod (mine)
LE Ghost Widow (opposing)
V Scarlet Witch (opposing) on last click and next to Deadshot

I mind control Scarlet Witch, with Gorilla Grod, to attack Ghost Widow, I roll a critical miss KOing Scarlet Witch. Does Deadshot get a die of healing?

yes, since scarlet witch was a friendly character when she was standing next to him, he would get a die of healing.

good question.

I would have to disagree with you because of the pulse wave clairfication
Because Sucide Squad has been ruled to take effect after the resolution of the action, you would not be able to use it in this instance.

That's what I would've said, but I wasn't 100% sure.