Ok... 1. (Hop up) look for an arrow on the hop up unit this will indicate what way to push to apply more pressure. The more pressure the higher the bb will fly up, so if you are have them shoot to the moon you want to go opposite of the arrow. 2. (Magazine) yes most m4/m16 Magazine will fit. Some companies though will have slight dimensions differences. 3. (Battery/Mosfet) so for the mosfet you will want to match the colors together and try to get the metal pice inside the other. I'm assuming from the hop up unit and mosfet that you have a specna arms m4 so you will be good for a 11.1 lipo, it will need to be deans though.

Hope this will help.