I don't think the mission is there to do again, at least in terms of layout and enemy/curio/obstacle spawn points. Most of the missions are random except for bosses, and they reroll after an attempt at a dungeon. The available missions are always a function of your average level... once you start having some guys hit level 2 you'll start seeing level 3 Veteran dungeons. Do not attempt those yet until you can get your weapons/armor to level 3 though.

> but i imagine that eventually you need to start investing in skills upgrades for your "favorite" characters.

Yup. Once you get the hang of clearing dungeons with minimal stress, start investing gold into skills/gear. Prioritize the hamlet upgrades that reduce costs because you will be spending a LOT of gold on these.

And once you start going on Medium/Long dungeons, you'll have some big runs where you can bring home 15-20k in gold. At this point it might be a good idea to start targeting guys for your A (and B, and C) squads. You can then start leveraging your Sanitarium for their quirks. Bad quirks are cheaper to remove than locking in your good quirks so early on you may just want to remove the bad instead of locking in the good. Note the red skull next to bad quirks... if you take someone on a run and they end up using that bad quirk a couple times then it can get locked in, making it much more expensive to remove at the Sanitarium. Removing/locking in quirks also become much more expensive once they hit level 3, then level 5. So there's a balancing risk/reward act if you want to save money treating quirks when they're younger but at the risk of them dying early.

> also, i don't think i've ever been able to camp, which would help reduce some of the in-campaign stress.

Camping is only available on Medium (once) and Long (twice) dungeons. Agreed, some of the Medium runs you'll do are actually easier than Short runs because you can camp. Some classes' camp skills are fantastic for relieving a ton of stress.