Good luck, OP, they are a delightful breed. My sister has one, and he is the most tolerant amiable dog going - although make no mistake, they are clever and need firm training, or they will train you, as my sister's has trained her. 
How do you get your choice of the litter? - ermmm, you breed it LOL.
Speaking personally, any breeder who would give me the choice of the litter unless I knew them very well would be a breeder I wouldn't want to buy from (bar the possible circumstance of you wanting the opposite sex puppy to what they intend to keep). A breeder who is prepared to give just anyone first choice is breeding for money, pure and simple.
Also note that the Miniature Schnauzer - a delightful breed when properly bred and reared - is a prime puppy farm target because of its popularity. Please do your homework and make sure you do not support this evil industry.
Hopefully a kc registered one.
Just for clarity, there are no good reasons why a pedigree puppy should not be KC registered - but there are many bad reasons. Some of them are as below:
- Bitch too young or old to have puppies within reasonable welfare standards
- Bitch has had too many litters for reasonable welfare standards
- One or both of the parents not KC registered - maybe because there were health issues and their pedigrees were endorsed to prevent breeding
- One or both of the parents were stolen
Anyone who states that they aren't KC registering because they want their puppies to have loving pet homes is just talking cobblers. No-one would knowingly reduce the value of their puppies if they had an option.