8 yrs of age is eligible for the Veterans class and I believe she can be spayed and shown in this class.

I am not shure what to tell you about her getting
along with your brother or Beanie.
I would say talk/and gather as much info. as you can from
the breeder about her.
Hopefully she just needs a few days to get use to her
surroundings, but if not make sure the breeder
will take her back.
Some breeders sell or give away their older show dogs
to make room for new ones.
IF homework is done to make the right match than
the senior dog has a good forever home.
I realize it is hard on a dog to be returned
back to the breeder, but you want to make
sure she goes to the right home for her senior years.

JMHO