What an adorable little girl!
I am not an expert by any means. I kept Mikey in his x-pen in the living room during the day and put his crate in there too and then moved his crate to our bedroom at night and he slept in his crate by my bed at night. I did have to take him out around 4 am for the first week or so and then he slept through the night (until 7, when we get up). Jen's advice is good. Don't take her out on every whimper, she'll let you know for sure. Will your son wake up to tell you if she starts whimpering to go out?
Also, the first few nights I would put the crate by your son's head so she feels safe and he can stick his fingers in and calm her. When they first come home to you, they can be a little scared at night because they are used to siblings around and it's all a new environment but if your son says "it's alright, I'm here" and touches her to comfort her, she'll be fine
Read up on potty training, I must have a dozen different books and read them all and used what worked best for me. I am lucky that our living room doesn't have carpet so as long as I watched Mikey like a hawk, he didn't pee in his x-pen or crate. I think it would have been harder if there was carpet under him.
Most of all - have fun with her and relax. Love her and play with her and you will all bond with her
There are also good books on crate training too