I've played Diablo 3 a bit when it was released. Is it possible to reset my achievements, quest progress, artisans and everything to have a fresh start with Reaper of Souls?
If you have a region where you haven't played before you can change your region and start with a completely blank slate.
Everything is region specific. Achievements, gold, friend list, characters, artisans, ...
The only nuisance is that the launcher does not properly switch region (the dropdown stays changed, but it still shows your online friends from your "main" region).
I've never had any lag concerns while playing on the US servers based in Europe. I can't remember how good/bad the Asia servers were since I only played on these when the EU/US servers were both overloaded during the initial launch.
You won't find this information on any Blizzard forums or help center (because it is not something players normally want to do).
However I would recommend to open a help request ticket. explaining your case. You are much likely to have a answer from them. Either it is positive or negative, in which case you will have a reason why it is not possible.
The only option I see would be to buy the game again under an other Battle.net account or the same but on a different region.