I certainly didn't do the skirmishes, but I did go through the entire quest arc. Despite my noobishness, poor build, and poor reflexes, I did manage to get through the boss fights without getting killed. I'd say it's fairly solo friendly.
I voted for the Salvatore quests, just because I don't care about the other things in the list. I'm just about to start those quests. At least, I think the quests I just accepted are the Salvatore quests. I'm a new player (having plowed through quests to level 60), and I don't understand the tradebar store. The gear…
Well, after that early gap, I haven't had any problems. I caught up and even got a few levels ahead of the content. If there was a soloable level 20 mission hidden somewhere, I couldn't find it. It's not a big deal, though.
I created a second character, and was much more careful monitoring my progress through the levels this time. And... I ended up exactly the same way. Level 18 with nothing but a level 21 mission available. Huh. I filled in the gap a bit with my first character with foundry missions, and I'm only behind by one level now, but…