Precum is pre semen. Just like when a woman gets sexually aroused so does a man. This happens so there will be lubrication so a couple can have intercourse.
I can't give you an exact answer as to how long sperm lives outside of the body. I've read that it can be 5 minutes to an hour. I question the hour because sperm needs a moist environment to survive. At an hour it would be dry and dead.
No, you could not have gotten pregnant by what happened.
Before you have sex you should get more sex education.
All I did was poke his penis.