> Is a testing project going to last 3-4 weeks and store answers?
No a testing project is only for testing the software, not for collecting data.
With the background you, by and large, define if you use www.soscisurvey.de for free or if you will have to pay. And this as nothing to do with the features, but with the question, if you are entitled to use www.soscisurvey.de for free.