Hey guys, Im about to start writting a fic based around Grindelwald's year's of terror and I need a few details to be checked out for me.

Where was Grindelwald from?

Is it ever actually confirmed...

1. How many countries he managed to take?

2. If he ever managed to get into the Brittish Wizarding Community?

3. How many followers he had, and what there "terrible actions" actually were?

4. How Dumbledore managed to defeat him other than that it was in a duel, no mentions of spells, spies, battles etc?

I just want to know how much space I can work in without changing anything that is specifically said in the books.

If you can think of any other information which would be helpful for me to know, and is specifically from the books or from interviews, F.A.Q's etc which J.K has answered herself then please add it here as it would really, really help me.

Thanks guys!