A good place to start is with the CKC and your local Boxer club. It shouldn't be hard to find a puppy without it's ears cropped. Most breeders leave that up to the owners unless it is a "show" quality dog which comes with a "show" contract. Tail docking and dew claw removal is done at a very young age so the tail will be docked unless you purchase your pup before birth and have that arranged. You shouldn't have too much of a problem getting a female; last time I looked into another boxer, flahsy fawn males were the hardest to get. Good luck, boxers are awesome!
My boxer/rottie or dobbie cross, we're not sure as he is a rescue.