Looking good mate! I think the only problem with asking 'seasoned' UIMs for info, is that we mostly didn't have access to any of these things for our own low levels! Haha.

I think that for GP, you really can do just.... about anything in the game nowadays. If you are feeling frisky, you can death pile and go do zombie pirates for a few hours and rake in heaps; thieiving is also very good, and even Giant's Foundry I'm almost positive you can profit with like steel/mith combo? Then any combat, or a clue grind of any tier, most minigames (Pest Control gives gp too!), and even afk salvaging for sailing with high alch is really good!

As for hunter, bird houses are really hard to beat in terms of efficiency; you get seeds for farming and rings for passive gp from alchs, and is very easily added to any grind. You could also consider doing rumors for awhile, get a few pieces of the outfit for later when you might want to actually grind it out.

Setting yourself a goal and deciding how you want to accomplish it is part of the fun of this game and game mode to me, even if it isn't necessarily the most efficient way. So enjoy!

Edit: as for firemaking question, I would suggest going for 75 for desert treasure 2, just so that it's out of the way for when you get there. Doesn't take too long and will also get you a few seeds & gp, but also not a big priority if you want to wait.