1, There's not much point into reroll ur character back to make it easier, as you said, high level gear are selling for alot more, but once u get to MQ level you can mq and start over, going above 80++ is just too hard with "bad" gear and not worth it it at all as your speed would drastically go down.
2, Yeah, doesnt hurt to sell guild points unless u wanna get ur own guild and try to rank it up the list urself. If u ask me i prefer playing together with ppl as that is more fun (chitchatting on voice etc makes it far more fun to play) Whenever I'm alone i prefer to skill and watch tv-shows/movies instead of climbing.
There's normally a few guilds out there that pay for GP atm, i think MO (Mount Olympus) does at least ask Mr
, i think there's other guilds too but i never really paid attention to them
But to answer ur question, yes alot of ppl join those guilds and sell points, some guilds might even lend out gear to make it easier for urself to progress up to MQ lvl.