Picture was a requirement, but that is slowly becoming less popular. Especially in Tech. Leave it off if you don't feel like including a Picture. I stopped including a Picture as well some years ago and it has not harmed (or improved) me yet.
Which other personal information is required? I would expect contact information and Name. Of course also your Work History and Education. Which personal information do you have a problem with?
> the requirement of a reference letter from your previous employer,
Yes, they are required to give you a reference letter when you leave the company. Honestly, I have never been asked to provide said letter to my new employer in the 15 Years I have worked in Germany.
Most times I don't even have one during the hiring process since I am still working there. So, even if asked about a reference letter, I would just reply that I do not have one. Which, again, has not happened to me yet.