No and no.
You can heal some, sure, but I'm pretty sure it won't be anywhere near to be able to be the main healer for FPs, especially later on.
With the Infiltrator fully skilled up, you're almost as fast as you would be without stealth, but not just. You'll be running at ~97,75% of the speed you otherwise would, due to how the math involved seems to work in the game (100 * 0,85 * 1,15 = 97,75)