Ok, I know that spells for your class will be permanently learnable after everything is finished.

Question 1: Does this apply to critter spells such as shadow web?

Question 2: If it does, will shadow web be learnable by ANYONE, or just moonmages?

>Question 1: Does this apply to critter spells such as shadow web?

Only some. Shadow Web is considered to be a moonie-spell, even though the guild leaders don't teach it. So it could be permanently learned by a moonie only.