Considering a period consists mostly of blood, the answer is obviously red.
Yes. All female mammals have periods.
If it is a female it might be having its period.
Yes with larger dogs there can be a smell.
No, it is not. But your young female may.
A female is in heat about 2 weeks from the beginning of bleeding
Nothing they go back to their happy normal selves
They can be bred when they have their first heat cycle which can be as early as four months but is more typically around six months. It is generally not recommended to breed a dog on it's first heat.
He will try to mate with her, stand up on her back & hump her. If she is not fixed she will get pregnant.
A bad day...
The yellow is recessive.
She is bleeding because she is on her period. That means, she is at the age where she can be breed-ed and have pups.
She may be marking her territory.