So, the Hunter can teach his animal Skirmisher Tricks in addition to the normal tricks an animal can learn.
Can he only team his Animal tricks that involve the animal such as Heel, Bolster Companion, and Sic 'em?
Or can the hunter teach the animal any of the Hunter's Tricks they could use such as Vengeance Strike, Upending Strike, Chameleon Step, and etc?
The big problem with option 2 is that there are Skirmisher Tricks that DO NOT work for animal companions. Like anything involving Ranged Attacks or giving advice to other people...
So, anyone know the answer or is it as entirely up to GM discretion as I think it is?
No one?
Your AC can learn any skirmisher trick. As you point out some are less useful than others. At a minimum I would avoid any involving getting an animal companion to do something (your AC doesn't have one) or ranged attacks - unless you've somehow acquired a manticore animal companion :)
I personally like the aid heal one - antiseptic licks?
YMMV