general wrc rally questions

[Mirek]

First, how many recce's do the crews do, see the stages only once, or twice?

Twice in WRC and ERC, usually three times in national events but it depends on local rules.

And what i also always wonder about when i am at the stage's, at what time does the first car start after the zero car has left the starting line?

That depends on the stage length. It can be five minutes in case of a short stage or it can be way more if the stage has 50 km. The first competitor shall never ever catch the zero car (even though it happens from time to time) but the gap shall not be bigger than necessary because the more time pass the higher probability that something isn't alright anymore (people walking in stage etc.).