How to make a good Partner Machine

I've got this game for christmas and i'm trying to work out a plan for making a good Partner Machine. specifically the GH-450 (i'm after a good mage to take on free missions)

I know that the best way to do that is with Photon Art Discs and clothes.

but before i do anything i need to figure out the order to develop the different levels in.

and at the same time I also want to be able to bump up the synthesis levels of all 4 in order to increase my chances for success on synthesis.

and I also need to know if i can continue to feed my partner machine items even after its reached its final form.

help?