do I need to include a data regulation/privacy disclaimer in my survey?
That depends on whether you handle personal data: Personal data - the GDPR applies independently of the person or company who is responsible for processing.
Will SoSci provide the data regulation/privacy disclaimer to include in the survey?
No, because the information you must provide accoring to GDPR is highly specific to your survey, for example the contact details, the data deletion schedule, the usage of the data.
They will click on the link and then go to the survey and complete it. Is that possible?
Yes.
I already have my questions ready or do I have to use questions from SoSci?
You will have to enter your questions (texts and options, for examples) into the user interface of SoSci Survey.
Does the SoSci interpret the data for me or do I have to do it manually?
You will have to do that, using a suitable statistic or qualitative data anylsis software.
When using the pro server, you can access descriptive online analyses.