You can print your thesis at the Computer Science Students' Representative Council of Saarland University for the actual cost that is generated by prints in the chosen printing period. You can find prizes for printing your thesis here.
Yes, you can work at the company longer than required, but there will be no additional credit points.
The employer just has to provide a document that contains the name of the company, the name of the intern, a brief job description (e.g. software development, interaction design, etc.), the duration of the internship (overall and weekly work time) and a signature of a person that is responsible for personal (e.g. supervisor, HR department, etc.).
No, you can just attend the talks and confirm the participation by signature. After you attended 3 talks and your own talk please contact the Team Assistance and provide the certificate of the employer and your student ID.