Well, I could've made it a bit more clear - level design was done in the last day.
In the starting pit, there is a red door (which requires a missile to open - metroidvania "rules" :) ). There is a door code behind it, the player can input that code to the door above: Approaching the circular device lets you interact with it, and your power settings work as the "code".
As for the air rolls, *after getting the artifact*, you can freely do somersaults while in the air. Look around with the mouse to see the effect. Plus, you can roll using Q and E.
Cheers!