From: Rochester, MN
Reply to Q1.
The way is, DONT click on the merc ever.
Once you click on him / her, they'll lose blood.
I have one merc having 8 health point left and I didn't click on him, not even to escape, leave him on that spot.
Luckily, no enemy squad shoot at him and was healed afterwards.
So, better wait ya team doctor to walk towards that merc and cure him, in the meantime, use "lying" mode.
HOWEVER, once he's healed on the field, the enemies would start shooting at him again, so, that's why I never bother to heal critically injured mercs.
Sounds like a bug to me. Or at least a poor design decision. I would prefer the merc to lose blood unless he/she gets treated by a med kit.