Yeah figuring out the input mappings for the Vive was a little tricky since the Vive wands are different than pretty much every other controller, plus I couldn't test it myself. Also makes it difficult to explain the controls since it's different for every controller. I'll have to put some charts together at some point. Down should be the button to activate the guns, and right should be the 180 flip. If you have any ideas for better Vive controls I'm all ears, I was mostly just guessing.
I don't have an issue with the sound stopping when opening the Steam VR menu so that might be on your end.
Also the shield and lightning is already in the game :P Unless you're just referring to the additional lightning abilities I have planned. But if you couldn't figure it out I try to explain it as best I can in the controls video.