Mechanically, the only thing Beast Change does is to allow you to create an alternate allocation of your skill points, with the special effect that you have an alternate shape when you switch between skill sets. It only allows you a single alternate shape with a single linked skill set.
A character with Beast Change and Inhuman Strength is technically Inhumanly Strong
all of the time, not just when he changes shape. This is fine for a Fae, because they are allowed to have such capabilities. It's the Human Form 'power' that causes those abilities to be limited by shape; if you take Human Form, then the abilities you link to it don't work unless you're in your non-human form. And you get a point of refresh back because you've limited your powers in this way (ie, Human Form is +1 refresh). Human Form can also be a benefit in some cases: if a character has Claws or Wings, for example, those are normally always obvious (no retractable claws!); but with Human Form, they 'go away' when in human form.
So if your player's build is:
- Inhuman Strength [-2]
- Inhuman Toughness [-2]
- The Catch: Fae Stuff [+1]
- Beast Change (insert alternate form here) [-1]
then he is always strong and tough, and can (separately) change into an animal form (with a corresponding skill change, generally to boost skills like sensory skills and physical fighting skills, and still keeping the Strength and Toughness). If, on the other hand, he chooses:
- Human Form [+1], affecting:
- - Beast Change (insert alternate form here) [-1]
- - Inhuman Strength [-2]
- - Inhuman Toughness [-2]
- - The Catch: Fae Stuff [+1]
then in his normal form does not have the Strength/Toughness powers, he only gets stronger and tougher when he changes out of his human shape. He can also mix and match, like this:
- Inhuman Toughness [-2]
- The Catch: Fae Stuff [+1]
- Human Form [+1], affecting:
- - Beast Change (insert alternate form here) [-1]
- - Inhuman Strength [-2]
Now he's always got the Toughness power, but Inhuman Strength is only available when in his beast shape.