Thanks for the review and congrats on your first place, let's see if anyone manages to beat it ;P
The player getting stuck on the platform is a bug turned into a feature basically. You can use it to place a platform, jump and stick to it, let the enemy pass below you and drop down again to continue. It can be used in some places where the enemy is moving horizontally.
You are correct though that the Zero Friction physics material would fix it.
Coyote time is in there but I must admit I did not spend a long time finding out what a good interval was, perhaps the time is too short. Jump buffering is not in there indeed, would have made the controller better so you are totally right there :)