When buying a border collie puppy how can you tell if it will be rough or smooth coated?

I’m getting a border collie and I want a rough coated dog. How can I tell if the puppy is going to be rough or smooth coated?
I have a friend who has a border collie that is smooth coated, so how can they only be rough coated?

Would it be ok if i brought a german shephard puppy and a rough collie puppy together?

I love both breeds and can spend as much time as necessary.

Would they be ok
I would get two males and get both neutered

Is it better to get them together or wait

how often can I bathe my puppy?

I have a shampoo for puppies. She is a 3 month old rough collie.