In rough reverse order, Aribeth, you can be a Night if you want to be.
Muse, we'll give you both of the ranks in Thaum for the cost of one (if more people take it, we'll go further down in cost), and for everyone, since it was asked... Maestro, if you would.
The major industries of Three Tombs Court are mining, exploring the tombs for profit, and very, very rarely, hosting large scale Scavenger Lord attempts to break into the tombs and get more stuff.
The Bright Day Tomb is the most explored, because it was made to serve in equal parts as a tomb and a museum. Every room can be gotten into and looked at. The treasures in the rooms, though, are usually locked up, and the guardians of the place are fierce and frightening things made of essence and glass.
The Shifting Tomb is probably the least explored. But seeing as the layout changes randomly, it might be that all the rooms have been seen, but nobody can confirm it. The tomb seems to give more detail about the tragic lives of the three that are buried in each tomb, but a wholly coherent narrative has yet to emerge.
The Still Tomb is the other contender for least explored of the three. Many of the rooms feature deadly traps, some strong enough to slay or turn away the Dragon Blooded. And when the Winter Folk come too close, it is the Still Tomb that turns bolts of lightning or gales of iron rain against them.
They are all made of the same clay, only painted golden, silver, or purple, respectively.
EDIT: Shadow, go ahead and post them. My usual houserule for when nobody's very focused on Crafting is that each craft after the first gets a cost discount of half, cumulative, round in your favor.