Grappling Stirges

Please help me clarify how the Stirges grappling works for tonights game.

1: The Stirge attacks with a touch attack that if successful means that it's grappling, without provoking an AoO or needing to win a grapple check, correct?

2: If it's still attached/grappling the following round, it starts to drain blood. Does this blooddraining count as a standard action?

3: If it detaches on a round in which it drained blood and flies away, does it provoke an AoO for leaving a threatened square?

4: Someone grappled by a Stirge can either deal non lethal damage or draw a light weapon by winning a grapple check, or deal lethal damage or attack with a light weapon by winning a grapple check at a -4 penalty, correct? (I know there are other options, but I just want to make sure about these.)

5: In the Stirge writeup in MM p.237 it says that you need to pin it to remove it. In the grapple writeup PH p.156 you get to pin by winning a grapple check. Isn't this equal to Escaping from Grapple by winning a grapple check?

Thanks for your time!

1. I believe so.
2. Blood Drain is a free action.
3. Probably depending on it movement.
4. Yes you can. And the Attack Your Opponent option does not require a grapple check just an attack roll against the stirge which has lost its Dexterity bonus to AC and has an AC of 12.
5. In a sense yes but you can not use Escape Artist you pin your opponent.

Just don't for get your size modifiers

Thanks for the help. Everything worked out smoothly, with one of the Stirges escaping with 4 Con points worth of blood in it's belly