I really want to love this game but I'm having trouble. I'm only five hours in and I just am not sure how to proceed. I don't know what's important and what I should be prioritizing.
I just got to the point where the introduction seems to be over; my team told me I can accept missions, decide who to take, etc. I met the potato guy.
Try to do whatever you enjoy. Complete a mission if it feels like fun, let it rot in your mission list if it doesn't. If it's a kill/fetch quest, chances are it gets completed anyway, without you really thinking about it. Explore, get killed, laugh it off and explore some more. Dig through the menus until your brain bleeds.
I dunno, this worked for me. You really shouldn't worry about "what am I supposed to do" too much because the game isn't really structured that way anyway. It's you on an uncharted planet where danger waits around every corner. Have fun and learn stuff along the way.
Class, I think. Definitely not level. I can see where the level requirement is.
Class selection screen. It tells you the associated weapons.
Once you max out a class path, you can use those weapons in any class.