I know many German companies require you to store data on servers also located in Germany. (But I have no idea if it's similar in other countries.)
Is it within Germany, or is it just within the EU?
Restricting it to Germany would seem anti-competitive on an EU level, which is usually not allowed. But I don't know the laws.
Depends. But if there are rules about keeping it in-country, you should consider storing it not at a storage provider.
Mostly, it is important to keep the data in the EER. So germany is fine. Moving data out of the EU is a big issue, although I have been using B2 but encrypt my data first myself.