Probably would be able to tell them what you want and they can get the closest thing for you. Thing that sucks about live is they are always growing so I'm sure it will be hit or miss if they have the right size depending on how many rabbits they are breeding. Might want to try a pink to see if she will take it. Sometimes it takes a bit to get them onto rabbits, however sometimes they take them without issue. Also if they don't have the right size you could always give her a rat that week.
Yep shouldn't be an issue. A rabbit pink is about the size of a rat pup so as long as they can take a pup they should be fine.