ya the 80 wt in the front is standard gear oil, for MX bikes or what ever, you can get it at an auto parts place, I know I got it at Canadian Tire in canada so I dont know what store would be the same in the US,
the green springs will probally be fine front and rear, that set up evolved from a different one where I had blue front and green rear, and then I wanted more rear traction on the back so put the blue there too, I probally could have went green front and got the same result more or less,
also the Mugen springs fit the CEN shocks, so if you are familiar with them you can use them, I'm not sure how they compare to the CEN spring rates thgouh, other than that I'm sure you can make any set of shocks fit the truck with a little work, but I have heard of someone running the mugen stuff on it, not sure what all was involved thgouh,