I’ve never heard a fellow canadian use huh. ever. I do hear both eh (A) and heh (HEY) quite frequently. I agree they are typically used as you describe, at the end of a sentence seeking agreement or acknowledgement, but like you said when used alone it is means “what was that?”
huh, is actually used almost identically, by it self for the same “what” meaning, or at the end of a sentence for agreement. You like that, huh? Pretty good, huh? They just don’t use it that way as commonly. 
One thing I cannot stand is how my fellow canadians pronounce pasta and orgami. They should be PAWsta and oriGOMi, every time I hear the nasaly oriGAMi or pAHsta i cringe. Not everything has to have that hard A, eh?
I love the Japanese use of ara. That is a great huh alternative. (Especially the mascunlized version oro which we see in commonly in manga)
