He's got Witchcraft for tradition. So not sure about drain on that. But, yeah, maximum bound spirits... Hrm... Might wanna make strength yer dump stat...
He's a dwarf - Strength: 3
is one of his dump stats. But the limitation on bound spirits doesn't really matter, when he doesn't even have the binding skill yet.
Hedge witches are normally women, but it does say that exceptions are made if a witch lacks a female heir and the line is is danger of being lost. They are wary of mentor spirits, so the character would have an ambivalent relationship with the rat mentor spirit (it would be considered helpful but still not completely trustworthy).
I think he is limiting himself a lot by picking a self-possession tradition and expending a lot of resources on animal control which are redundant with the two spells he already has for that.