You can get a long term car lease for a brand new car instead of buying. It's much easier and it includes comprehensive, no excess insurance. The cost comes to about what you would lose on depreciation. You just need to go directly through the company - we used Peugeot but Renault and Citroen do them too. Someone rear ended our car and they arranged a rental car for us until it was fixed.

Visa? Me and my boys have EU passports so we can stay as long as we like and so can DH because he is married to me but we still had to register with our local marie.
We took a long term lease on a property and then used it as a base. So we had a home of sorts and home town where we could get to know the locals and the boys made friends with the kids from the town.