3. Don't fly inverted for more than 10 seconds.
2. Missiles need a lock. Press 'n' or 'N' to designate something with the radar. Then when their within range range use 'e' or trigger (if you have set it up) to fire. However there are more ways to fire missiles, like the IR missiles dont need a radar lock etc., but try this to to start with.
1. This is not easy explained in text. So I have made 7 videos that explains most of its systems: (they are best watched in order)
https://www.youtube.com/playlist?list=PLogi97V-ki0GfCLqimTtIq9RIVcm-GRFEI still need to make a video for using weapons, but until that is done, just ask questions here.