In principle, yes, but you should have made a correspondingly large substantial contribution to the publication and must indicate which parts are not yours.
No, the publications are included in the dissertation as they were submitted or already published, similar to a chapter. They can only be included as a LINK in the context of the subsequent publication at the University Library's University Press Office (instead of the complete publication).
Of course, composite illustrations with several parts can also be included in dissertations. There is no objective reason why this should not be possible.
You do not have to provide evidence of first authorship, but you do have to hold a prominent position; this is also the case for correspondent authorships. This applies to the required two publications accepted or published in the peer review process.
The English B2 language certificate must be submitted in advance. This is normally done as part of the application process. You can find out from your admission letter whether the language certificate has already been submitted.
