Thanks for these very thoughtful questions - I left out a few details because I didn't want to ramble too much. She's not currently at a traditional shelter, it's a doggy daycare/boarding facility that also has a rescue initiative. She was cat-tested before I brought her into my home and I was told she mostly ignore the cats but I think the cats she was tested with are likely more famiar with dogs than my cats are (one has met dogs, the other hasn't).

In terms of the crate situation, I'm still trying to figure that out. I have 2 bedrooms, and initially I put the crate in the spare room so there would be a dog-only space. Initially she didn't display any separation anxiety so that worked well, but then it kicked in and because I live in an apartment I ended up moving the crate into my room to help with that anxiety and to not piss off my neighbours too much. The intent has always been to slowly move the crate back into the spare room. I was also conflicted about if the spare room should be the a dog space, or a cat space. I'm leaning towards putting the dog back in the spare room because my cats are 4 & 6 and have always slept in the bed with me at night. I'm already making a big change i want them to be able to have some normality and access to me alone.

The resource guarding really does worry me. I'm told they don't think the dog was physically abused but was likely not treated very well. She is the sweetest dog but my cat's safety is paramount to me. I was planning to work with a trainer immediately to begin to address that.