Both of mine are around 50-55 pounds; one 8 years old, the other 4.
you can go to your local animal shelter or contact a breeder. The phone book is the best place to look, or you can google search the internet.
they stop growing at about age two (thats how old mine is), and their back comes to about an averaged sized 11 year olds knee (me)
They are both very smart but black labs tend to be more hyper.
I've had my cross collie lab for about 15 years but she's very much on her last legs now.
No, Border Collies come in a variety of colours and markings besides black.
Choosing a Breed Dog
Dogs Beauty Pageants
How to Deal with a Misbehaving Dog
How to Groom a Collie's Teeth and Ears