Well, it certainly sounds like you are being very deliberate about pursuing feeding raw which certainly is a plus. I do believe even dry dog food can become contaminated with salmonella, this past August there was a big recall involving a few big name brands due to a salmonella scare.....so a dog might contract salmonella in many ways...raw or not.
It seems a dog which can be more at risk for contracting salmonella is one which might be on antibiotics for certain maladies....I guess the antibiotics in some cases kill the "good" bacteria as well, making the dog more susceptible.
Overall, I think salmonella in dogs is a fairly rare occurrence BUT...if it happened to my dog, I wouldn't think it was so "rare".
My current dog is the first to be fed raw for me. So far, so good and I'm glad I made the change.
I wish you the best in your decision process and since you seem to be very thorough, investigating the possible change in diet.....I am sure you will make the proper choice....whatever that may be.