This is still being decided but it will be anywhere from at least 6 months to possibly forever. The same goes for merges.
All regions will have at least one fresh start server. Specifics will be announced closer to Nov 2 so folks can plan, but for sure there will be at least one in each region along with a third character slot so everyone can join without having to choose which legacy character to delete.
We do need an FAQ, because we would like to answer as many frequently asked questions as we can at once, in a meaningful way that is localized to the languages we support so everyone gets a chance to comfortably read through the responses that are most important to them.
The FAQ will be out close to Nov 2.