Males can produce sperm as early as 6 months of age, but the sperm is usually of small number and of poor quality. As the dog matures the sperm become more numerous and their quality improves. You should never breed a dog (male or female) until they are AT MINIMUM - over two years of age and have the proper health clearances, titled and purebred. When breeding you only want to breed those specimens of superior quality that have proven themselves either in the show ring or in work against those of the same breed. Breed to better your chosen breed, not destroy it.
they go through doggy "puberty" around 6 to 9 months, and after that they're fully functional
i think about 4 or 3 because they get their parts then
dont get a male dog
Get her spayed, or keep her inside, and away from male dogs.
From around 6-7 months of age providing testicular development was normal.
Your male dog has to be atleast 2 years of age to be studded out well mated with another dog.
4 years old
If your female is not "breeding" it could be age, species, or not her "season".
Are the dogs in heat? Panting is typically either a sign that the dog is hot, stressed or excited. I am assuming your dog is male since you said "another" male. The other male may be dominant and your dog may be somewhat stressed by the situation which would certainly cause him to pant.
cause it loves it
Your Labrador male dog should start barking at strangers when it is at least 12 months old.
114 in dog years
No. Only a male can impregnate a female. No female mammal of any species can get another female pregnant. For mammals that have a "heat" cycle, being in "heat" is required for pregnancy by a male. If such a mammal (a dog for instance) is not in heat or doesn't have a male partner, pregnancy is not possible.
Probably not - the first sire's DNA would be long gone from the uterus before the second pregnancy was started.