Glad you like the board
Depends a bit on your weight (and height/stance) but in the lighter half of the board's windrange (or more typically, in flatter water and less vertical chop) the full back stance is usually faster. As the wind/chop builds (and correspondingly more power thru the rig, and rougher water) it's usually faster with the mid position, allowing a calming action onto the board while still providing heaps of leg drive.
For the mast track, with sails around 7.2, most conditions you will be fine with it right in the middle (50%) of the track. Initially this may leave the trim feeling just a big flighty, but a few runs and you should be fine and not looking back, In serious control situations, with very vertical chop, moving fwd 1-2cm wil help you plaster the board down onto the water, but for best speed in allround conditions with 7.2, try the middle. Once you've got any sort of decent power into the 7.2m, try the 34cm fin, the speed will take another surge.
Cheers ~ Ian