I tried Googling "Kant 'notions'" but that doesn't seem efficient (from the results I've gotten). I assume that he appealed to the word for its being originally cognate with noesis and the like, although whether he used it often, I don't recall, nor whether he always used it in line with his one-off definition of notions as formed by the pure faculty of our concepts (the understanding), with reason forming ideas out of notions.
Where do notions fit in, exactly, alongside concepts like type of the law or formal intuition, in Kant's network of kinds of representation? I doubt they're types as such, since Kant seems to assign types to pure reason, whereas notions have more purchase in the understanding, and they're not formal intuitions of course, but could they be on roughly the same "level of abstraction" as types and formal intuitions?