i know some pits may become dog aggressive and may not like cats but out of all my years with the breed i havent had that problem so im hoping it wont happen with this one. and yes i do have an alternative if that does happen but with good training and good socialization that shouldnt happen..
Training and socialization will make for a happy and obedient dog, but it won't do anything to stop dog aggression from presenting in your dog.
You most definitely can manage DA, but you cannot cure it nor train it out of your dog.
You really need to be aware, and never get complacent, as DA can all-of-a-sudden appear at any time. I've had dogs exhibiting DA at 10 months, and I've had one that didn't turn on until 5 (and let me tell you about that bloodbath in my living room from her and a male that were loose in there
).
Fwiw, NONE of my dogs had/have tolerance for cats or little dogs (and I've owned a LOT of true APBTs). I've had some dogs that were pretty much cold (no reaction to other dogs), but even those dogs had issues with "prey" smaller than them. I've never, and never will, get an APBT with the thinking that it will be a "friend" to my other dog(s). I always bring them in as an "only dog", and then go about finding out whether or not it can be safely allowed to have some play time with another dog or not.
You're going to have to be really rigid and strict in your management of your pets, and remember that there's rarely such a thing as an "accident". Almost always it's a lapse in judgement and/or responsibility.
As for the guy you got this dog from, he sounds like your typical backyard breeder of "pit bull" mutts, meaning there's little chance the dog is purebred anything. All he cares about is cash in his pocket, and as long as people continue to provide him with such cash, he'll continue to pump out nondescript dogs in his backyard.