No. Sage (and FAQ?) has ruled that a Command to sleep, freeze, or die (etc) is equivalent to being stunned, not helpless.
No. Even pinned - in fact, pinned specifically says you're not helpless. You are, however, denied your Dex bonus (as in many of these conditions), which allows a Rogue (etc) to Sneak Attack.
You are unaware as your attacker sneaks up from behind - ?
No. Denied Dex.
No.
No. Denied Dex.
No. You consider the Charmer a friend... it doesn't mean you're going to stand still while he cuts your throat!
As a general rule for evaluating Charms, consider how the character would react if another PC acted in the same way or made the same suggestion.
For example, if Wally the Wizard suggested that you help him hack Fred the Fighter and Clem the Cleric into little pieces, you'd probably try to settle things amicably without resorting to violence... possibly even restraining Wally for his own good. Just because someone's Charmed you, it doesn't mean you're a mindless automaton.
Also can you do it in a fight when the target has allies nearby to protect him?
Yup. It's a full round action, but unless they have readied actions to prevent it, or use the AoO a CDG provokes to knock you unconscious, kill you, or somehow prevent you finishing the action (grapple, bull-rush, disarm), it isn't going to be prevented.
-Hyp.