Wow this is great!
I love your idea to use a string quartet. I think while every section is very unique they all flow in to each other naturally showing a high knowledge in composition. The piece keeps evolving and when a previous heard section returns it wells fresh which is very impressive. Good use of ornamentation and playing techniques. I think my only wish were for the cello to get a bit more variation and to get to join in on the fun, in such making the piece even more like a chamber piece. Then again there has to be some balance between a chamber piece in a song form. Personally I though it would be fun to lean even more into the classical/chamber aspect of the piece.
All in all I loved all of it and I felt that you managed to not only succeced in the criterias but go beyond them. This is probaly what I think is the strongest piece!