Rokurokubi and martial arts

[Kilmore]

I'm making a rokurokubi (Japanese monster with a stretching neck, see GURPS Classic: Japan). She has Stretching 3 (7 yards), neck only, Constricting Attack, and Striker for her head. I have some questions.

1. Constricting Attack works on a successful grapple. Can she use Judo with her neck? Or does she have to use base DX?

2. If she can use Judo with her neck, does it affect Techniques such as a Limb Lock, Choke Hold or Head Lock, or a Sweep?

3. Can she substitute Karate for Brawling when using her Striker (head)?

4. If prone, is she subject to the penalty for Ground or Low fighting when using her Reach 3 Striker?

5. After grappling with her neck, can she perform an Arm Lock in one turn, then go on to do a Choke Hold in the next while continuing the Arm Lock, at the typical penalty to multiple attacks?

6. She is normally human sized (SM+0), but her neck stretches out to SM+3. She can inflict a Constriction Attack on a SM +3 opponent, right?

Thank you in advance.