Arcadia is a physical place, yes - a domain is just, like, her house, or her property. It's just that when fae are so powerful and the rules of physics are a little bit nebulous, each fae's home can feel very distinct from the rest, and sometimes operate by different rules. It's all the same place, though, generally speaking. You don't have to cross between worlds to move around it.

She'll laugh, and say she's not sure if the Summer Court is as jealous as the Winter Court seems to be. Maybe jealousy is just a part of the court's design. She never knew any Summer Court until she met Moss, here at the caravan. It seems like the carnival has a Summer Court with them too, don't they?

There's not much hesitation in explaining her escape. Essentially, she had just been a trusted enough disciple to work at one of the Mother of Inventions colonies, set up on a mortal world. The Caravan happened to pass through while they were operating there, and got caught up in the whole thing. In the end, her and Scald ended up aiding and escaping with them.