To me, Luke’s death was less of a physical one. Not just simply death, but the moment Luke achieved nirvana. But to reach “Force nirvana”, you literally become one with Force, meaning no physical body necessary.

FMA, if you’re referring to why the Resistance is so shabby compared to the First Order, then my guess is that it is because the Resistance isn’t really being funded by the Republic as a whole. Maybe a few sympathetic senators are helping support them, but financing a private militia is $$$ and I like to imagine that by the beginning TFA, that Leia is already broke funding it herself. All she has now is 3PO and the clout her name holds, which by the end of TLJ doesn’t seem to be much.