The first one...I had a Doberman that I bathed once a month and she had a beautiful coat. I took her to the beach often, so if I did not bath her she would began to stink like seaweed and dead fish. And I hate "doggy smell as it is. Use a good shampoo that moisturizes. I used a natural oatmeal soap for her.
Number two...My short hair Chihuahua sheds like he has the mange. Shedding is COMPLETELY based on breed and not hair length.
Number three...as you mentioned it depends on the shot. The rabies shot is now a three year range. However, the shots that only last a year should be given, especially if you take your dog to a dog park or kennel where they have a lot of close contact with other dogs and their feces. Not all dog owners are diligent about pet health. Your pet could catch something.
Number four...I'm not a vet, but I've never heard this. I would think it would be on a case by case basis. Obviously, if the dog is too weak for anesthesia it is too weak for surgery. One should really consider carefully about putting an old dog through the trauma just to extended his life for maybe just weeks or months. They can't understand what they are going through like human can. Think about quality of THEIR life.
The last...this can be touchy. While I think if a dog has a broken a leg or some type of short term injury as such, then a bit of pain meds to ease him, is worth it. Dogs don't show pain like people do so just because we are "seeing" doesn't mean it isn't there. However, I do not think a dog should be kept indefinitely on pain meds. One should really consider quality of life in situations that would require constant pain management.