Thanks for the in-depth feedback! I completely agree that the controls aren't as tight as we wanted them to be, especially on walls. Currently the trick is to look at the wall you're currently on, then the controls feel more intuitive. Though that's never explained in game and certainly not how we wanted it to turn out
The functionality to drop abilities is actually in the game and can be used with the keys 1-5, as well as getting heavier and bigger the more abilities you obtain (and the other way around when dropping them) but it's very subtle. Unfortunately we didn't have enough time to properly use either in any levels.