With a Multiple-Entry Tourist Visa (METV) for Thailand, you can stay for up to 60 days per entry, but the visa itself is valid for multiple entries within a 6-month period from the date of issuance. This means you can enter Thailand several times during the 6-month validity, with each stay capped at 60 days, as long as the visa remains valid.
There is no German embassy or consul in Germany. If you apply in Pattaya, you'll find a consul named Hofer, who is equally responsible for Germans and Austrians.
Non O Retirement Visa for you if older than 50 years: You don't need a bank account or 800,000 THB in a Thai account. If you earn more than 65,000 Thai Baht per month in Germany, you can have this certified by your embassy or a German consul in Thailand. If you apply for a Non O Retirement in Thailand you need about 90 days. If you are successful, you can apply every year for a 360 days extension of stay. Once done and without breaking rules you don't need to apply for a visa anymore, only for the yearly extension of stay.
I don't know where you live, but even with a Thai driving license, you can't drive to your wife more often if you don't have the appropriate immigration visa.