doggy style. How did you think they do it?
NO
If the female is trying to get pregnant with a male dog then it will go on the males back but if the female dog is going on the males back while pregnant then it may means that they wanted to have another baby.
By mating with a male dog.
No
Sometimes.
Yes.
Often, a male dog is protective of the pregnant female dog, usually if he is the "mate." Sometimes dogs, mates of the pregnant dog or not, will act aggressivley towards the female dog, also known as the "bitch."
She could die.
No
If the male has not been neutered and/or the female has not been spayed, then yes. And unneutered dog can get any unspayed female dog pregnant.
Once the ovaries and uterus have been removed from a female dog, it is impossible for her to get pregnant. If a bitch 'believed' to have been spayed does get pregnant, it must then become obvious that the dog was never spayed.
Well, a female dog can get pregnant as early as 6 months...but it's not recommended to let a dog that young get pregnant, it's like letting a 10-12 year old human get pregnant...it's possible biologically but not good.