Alternator recommendations? (and other very noob question)

The retail availability and selection in Germany for lamps is probably a bit different than here in the U S of A.

I have nothing else to add as Dana described the situation. These cars were designed to start up on the battery and then run the engine and 'accessories' off the alternator. All those additional loads need to be wired into a completely reworked system designed to handle them. The headlight relay system is a must for durability and performance - unless - maybe with LED lamps since the draw is relatively low. The headlight relays can be done regardless because headlights are normally only used when the engine is running.