I need to identify some info about a participant (e.g., name, email, what course they want extra credit for). However, I want the rest of the info collected to be anonymous surveys about personality and behaviors). I am considering providing a link in the thank you message at the end of the study survey to another survey where I can collect that identifiable data. I've also considered asking for the identifiable data at the beginning then providing a link to the anonymous study survey - however, then I won't know whether a participant actually finished the study survey. Any thoughts would be greatly appreciated.

I think what you want to do is set the End of Survey action to redirect to the next (anonymous) survey. See: Redirecting Respondents to a URL

How can I keep all but two or three questions of my survey annonymous?

How can I keep all but two or three questions of my survey annonymous? | Experience Community