I forget what level Nisse's Lair is geared for, but 10-20 sounds about right.
Thidranki is the last BG with aurulite/kill task quests for now.
I don't recall it's name, but I do remember exping in a fort down south full of werewolves that was pretty fun back in the day.
Take a peek at the quests listed on Allakhazam for some other ideas. Typically aside from the BG quests from 10-24, task dungeons are the fastest way to level solo. Since it sounds like you want to avoid the TDs (I don't blame you for entertainment purposes, but they're hard to beat exp wise solo) I'd lean towards quests in the newer content... catacombs, darkness rising, etc, being more recent, they're going to give you the best return for your time spent.
Scales drop off most mobs in the dragon zones, I don't know what those zones are in midgard, but it shouldn't be too difficult to figure out. The slayer gear is pretty useful and very often shows up in high end templates.
I don't know when you can first start getting artifacts, but I would say early 30's for some. I know some artifacts, like the Gem of Lost Memories just for an example, are grey con to a level 50, so it should be pretty useable for a low-mid 30 character. There are level 30ish mobs in ToA as well, so if you can start getting the books I imagine there are at least some arties you can start using that early.
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