1. zoom
Zoom is making a high speed climb. It can be either 90 degree nose up or just 15 degree nose up, high speed before a zoom is paramount (otherwise its just climbing..and thats not healthy in a dogfight). For the P-38's zoom, be sure you have 400mph hitting the white needle.
2. hammerhead
Hammerhead is to change your flight vector in the vertical with little or no horizontal displacement (translation: plane flies straight up and flips nose downwards with little or no horizontal flying as the nose flips downward). There are 2 ways of hammerheading: By going to 10mph and 3 flaps out and pulling UP on the stick to flip nose over (easiest to do but also dangerous since your opponent will have an easy shot at your plane from the top of your plane) or to use the engines to make the 38 flip sideways (harder to do but the opponent behind you only sees your rear and side profiles during the whole manouver, you are a much smaller target).
3. wingover
I dont know what you mean by "wingover" , many folks call different manouvers that.
4. reversal?
This one covers a lot of manouvers. A reversal (for me) is to either change your flight vector very fast (like a hammerhead) or to go from being the one with the con in your 6 to being the one who is in the con's 6. Again, I dont know what you mean by reversal?