[Accepted to program with no funding details yet - when should I follow up?]

Funding decisions often come out of the dean's office. Departments get the budget when they get it. IMHO, asking about it now will serve absolutely no purpose, since you were already told the decisions might come as late as March.

[Funding for MA programs in Museum Studies]

Case Western Reserve University has an MA program in Art History and Museum Studies administered jointly with the amazing Cleveland Museum of Art. They admit MA students with full tuition and often with full fellowship for two years, I am told. Competition is tough by worth it.

[Should I drop out of my PhD program?]

On 2/12/2018 at 10:34 AM, HJones95 said:

I am not happy here. I have a tolerable relationship with my advisor but it has been fraught with difficulty and misunderstanding

I think this is the most important part of the post. It tells me that the OP is not going to fix the situation by adding another field or tweaking her field. Relationship with your PhD adviser is one of the most important things in graduate school. My advice is to contact your undergraduate adviser, who presumably set you on this research path, and ask about some possible ways forward. She/he would be in a good position to advise. Also if you really loved the promise of some of the MA programs that accepted you previously, maybe contact the professors in those and see if they might still  be interested in working you in the future. Like someone above said, everyone makes mistakes, and you are probably very young and have everything ahead of you! 

[Scandinavian Art]

Michelle Facos, at Bloomington, does what you want to study.

[Medieval Art Historians?]

Someone already said Case Western (Gertsman and now also Bolman) that has a joint program with the Cleveland Museum of Art and its awesome medieval art collection that has loads of manuscripts. They are object-oriented. Somebody also already said Rice (Wolfthal) -- late medieval and northern Renaissance manuscripts. Also object-oriented. If you want to apply abroad, consider St. Andrews (Rudy) and Courtauld (Nash and Bovey). I would just check out the reputation of any potential adviser in terms of their treatment of advisees / flexibility in dissertation topics.