I believe various denizens of the creepy castle will be at the Transport Log with baked goods and information about the castle - basically, you get a place to stay in exchange for renovation work. I had the idea of opening the museum part of it to the general (local) public, as a means of generating income. That means there would be a need for people who can clean and restore the art, work in the museum, or even create new works of art.

Making it into a proper base, with defense capabilities would have to be done clandestinely. However since most of the museum is underground, it's a fairly good bomb shelter. It might also be a place to protect locals, as Transports have a bad habit of visiting destruction upon Exsilium, oops.