So when a girl ask for time and space how long do I wait, before giving up?

Ask her! Sit down with her, tell her you like her, but tell her you also respect her situation, and understand her need for some time and space. Then ask her how much time and space she thinks she needs. If she says "a month", just nod your head, take her hand in yours, respond that she is worth waiting for, and that you will call her again in a month to see how she is doing. Something more or less like that. If she says " a year" or some other really long time, tell her you really like her, and that you understand, but that the timing is probably just not right for you two. Etc. That's a good way to handle things, I think. Good luck!

Depends on how much you like her. If you really think you have a potential relationship that's healthy with everything you want in it, as long as she needs. If not then it doesn't matter does it.

Things are different from person to person. But in my life experiences, when a woman wants "space", it means they want to do whatever they want without any accountability to you. Which means she is being selfish. Find someone else.

Perhaps it could mean something else entirely. I'm not exactly the most successful man in dating...