About the music, I've often tried in the past (it didn't ended well :),and for the sounds... I'd say I've been a bit lazy :D
But anyway thank you for playing (っ •ω•)っ
Probably ask a sound designer
Most of these folks are happy to do something for a cool game like yours (me included :) )
I also liked the level design.
The beginning was a bit difficult concerning timing (those first gaps) but I ended up with a lot of "wtf this is cool" moments in the end.
Especially the ending was really great imo
Really well done ^^