In the anime:
Videl finds out when she sees the great saiyaman get a cut from a dinosaur and then sees a cut on the exact spot as Gohan. She puts two and two together and blackmails him by saying that she will keep his secret if he competes in the world Martial Arts tournament and if he teachers her how to fly.
Gohan teaches her during The Great Saiyaman Saga.
I'm not remember but all I know is Gohan marry Videl after Majin Buu saga
Videl and Gohan got married because they were in love with each other, and as a result wished to be together.
no gohan does not have a son but he does have a daughter named pan and videl is his wife.
they dont
Yes after Videl know Gohan is the great saiyaman and after Gohan and Videl defeat Frieza(some how come back to revenge Goku)Gohan let Videl become the great saiyaman(maybe after the MajinBuu saga)
Great Saiyaman of course because Gohan is stronger than Videl...
Gohan teaches her during The Great Saiyaman Saga.
The name of Gohan and Videl's daughter is Pan.
Gohan doesn't train Videl in DBGT.
Videl in the anime seem as the same age as Gohan but because Gohan went in to the Hoibolic Time Chamber, he is likely younger than Videl
I'm not remember but all I know is Gohan marry Videl after Majin Buu saga
Videl and Gohan got married because they were in love with each other, and as a result wished to be together.
Videl first meets Gohan 5 years after he defeats Cell and goes to highschool. They later fall in love at the World Marshal Arts Tournament which ignites the Majin Buu chronicles.
Teen Gohan liked Videl.
no gohan does not have a son but he does have a daughter named pan and videl is his wife.
Gohan her boyfriend