I ended up getting the game for the 3DS, thanks for the couple of guys here who helped my nail down that I *could* do co-op with my brother! We didn't properly test it by doing any quests but I could see his guy listed on the bottom screen (couldn't see him on the top screen though, assuming that's not the case on the actual hunting grounds) so hopefully it'll work out.
Having much more fun than I'd expected though, having never played a full MonHun game and having had a bad experience with the demo (I had no idea what I was doing, basically). Got a better grasp of the basics now, rocking some duel blades, working out how the goddamn camera works, enjoying it,
. I've probably played about 4 hours and done absolutely nothing of worth - lots of jaggi hunting and mushroom picking - so the real monster hunting is yet to come.
Gonna have to get on the Wiki though.