I guess it was between 1998 and 2010. Maybe.
Yes. in the chapter 19 year's later they have three kids Albus,Lily and James.
The wedding reception was not explained during the book, but it is implied that harry and Ginny marry in the epilouge. It would be really cool if they showed a bit of the reception in the final movie.
Yes! They've been destined to be together since the beginning.
18 or more, we don't know. 18 thru 26 we don't know