第一题的解答: No one can give birth to unlimited number of kids, so 1:1 is wrong.
My assumption is that the couple will stop at 2 regardless we they have: The outcome is
One boy: 0.5
Two girls: 0.25
A boy and a girl: 0.25.
The male and female ratio is 5:3 in such a case.
第二题的解答: Again make simple assumtion: male and female all get married at 20 and die at 70. Old male always have priorty over younger one in terms of getting a spouse. If every male and female are matched today in the society. And boy and girl grow into their 20 at 100 to 90 ratio in the future. It will take 500 years until some man will not find a wife.