[3.5] Dire Weasel Attach

[Domigorgon]

OK, so my player who is a druid 6/beastmaster 1 has at this point a large dire weasel as his animal companion, to my great annoyance.

The SRD says this about a dire weasel's abilities:

Attach (Ex): A dire weasel that hits with its bite attack latches onto the opponent’s body with its powerful jaws. An attached dire weasel loses its Dexterity bonus to AC and thus has an AC of 12. An attached dire weasel can be struck with a weapon or grappled itself. To remove an attached dire weasel through grappling, the opponent must achieve a pin against the creature.

Blood Drain (Ex): A dire weasel drains blood for 1d4 points of Constitution damage each round it remains attached.

OK, so, every time the weasel succeeds in a bite attack, it automatically attaches to its victim. But what does that mean? Are the victim and the dire weasel grappling now? Can the victim move? Can the victim, while having the weasel attached, attack anybody but the weasel? Is there a penalty to attacks, and towards whom? Is the weasel's dexterity bonus denied from the victim's perspective? Does the victim threaten nearby squares? Does an attack of opportunity on the part of weasel also result in an attach? How do grapple and pinning behave in the Astral Plane (let's say that that's where they were)?

WHAT!?

Our last session was totally ruined with bickering over these questions and what exactly happens, and I wouldn't want it to happen again... Please, tell me how to deal with this.

[Iku Rex]

Are the victim and the dire weasel grappling now?

Yes.

The rest are grappling questions.