either lipo or nimh should be fine but i found out some people like nimh to give a bit of weight to the truck.

upgrades, u can start looking into alloy links, alloy shaft and shocks.
axial alloy links should be enough for the truck, as for shaft u can use 3racing, junfac, or mip alloy shaft.

shocks, depending on how high u want the truck to be u can change it to any alloy shock depending on the length of it.