However long it takes you to ejaculate. It differs with each male due to the PC muscle strength. I forget what PC stands for, but it is the muscle that contracts around the urethra and vas deferens that prevents semen from going through. It contracts earlier if weaker, and thus some men can't last as long as others, but there are ways of strengthening the muscle if you are willing to devote of a lot of time and practice to the exercises.
There are no required days of continuous intercourse for a woman to become pregnant. A woman may become pregnant the first time she has intercourse.
The more you do it the less swimmers he will have. The sperm can live in the fallopian tube for 5 days so continuous sex isn't necessary.
There is no set days it could happen on the first try