OMG Who knew finding a dog would be so hard?! Health now please. Rottweilers?

Hello allTo those who have seen me post a million and one dog questions I apologize. Originally I was dead set on a Boerboel because online everything seemed so perfect and as a rare breed I had never met one... then I did. Not the dog for me.So what I have decided: I want ideally a rottweiler although I would be fine with a Cane Coros, a bull mastiff, any tough looking dogs, you know the type? So after much research I find that dogs between 80-100lbs will have fewer hip problems than larger breeds, and after speaking to vets I have contradicting information saying mutts are healthier then pure breeds and vicea versa. So I begin my long search into Rottweilers and after contacting what appears to be a reputable breeder she says she guarantees her dogs for 2 years, after the health check if something is wrong we can go from there. Well after 2 minutes, let alone 2 years with a dog I will be too in love to just give it back if its got problems!So someone PLEASE tell me what to do! I want a bigish dog, I would like to avoid health problems where possible (I understand its not totally avoidable in any situation) I want him to be trainable and have at least a small amount of protective instinct. I like the short hair muscular look but that's the last thing on my mind at this point.Do you have a Rottweiler? How long did it live and what were its problems? Pure bred or mix? Just anything you can tell me about the breed or any other breeds would be great! Thanks....again!