Richy,
If you want to change strings, get a couple dowell rods/couple broom handles/just about anything the same diameter, and, at full draw, have someone insert them from the side in the area between the cables, the top of the inner limb, and the bottom of the outer limb. This keeps the bow drawn when you let it down and will let you swap strings very easily. If you're looking to do more than that, take the weight off of the bow by turning the limb bolts, alternating top and bottom, 2 turns each until you get the weight down.
As far as the modules go, they should be marked with a number or a letter indicating the draw length and let-off for that module. They will be the same module in all 4 cams, and as long as they are put back in the cam correctly, it won't matter which module came from which cam. If you have any other questions, feel free to ask. There's a lot of guys on here that can talk you through doing just about anything to this bow and are more than willing to help out!
Justin