When playing Survival, how do I know if I should revive my teammate? Sometimes I get into a room with people with no mics (i can seriously never find a room where everyone has a mic). I never know if I should revive a player or not. I know when I get downed, I would rather just bleed out to get my tombstone.
EDIT: adding a question: When a teammate has more than one zombie around them in the beginning rounds, is it okay to kill one?
You need to kill yourself to leave a tombstone. That means that the choice about whether they want to be revived or not is completely in their hands. Revive them if you can, if they have a tombstone, they'll probably kill themselves. Furthermore, they can always plug in their mic to say they don't want to be revived. Kill stealing pisses me off in any game mode, so I'd say it's best to not do it.
Depends on the lobby. If others are kill stealing, go ahead. If not, respect their boundaries. In terms of reviving, always have a backup route. If you run head first and go down, you're useful to nobody.
As far as reviving goes, if you can safely do it, revive away. However, if it's a risk, don't bother, unless it's someone who you think is a good player.
In regards to kill stealing, as a rule of thumb - just don't do it. It severely pisses me off when people do it, especially in the first few rounds when it matters.