Recommendations for user activity log

Want to log user activity for university course sites. Record log ins, node views (including time spent on page, if possible), exercise submissions, viewing feedback, other things. Need ability to add code for custom events (with, e.g., plugins). Include custom data in logs, like responses to questions embedded in nodes. Different log records will store different kinds of data, depending on the event. Might be in serialized arrays, JSON strings, or something else.

If possible, log user scrolling behavior, as they jump around in a page (to study student reading behavior). This is optional, though.

Will want to log Webform responses, too.

Output:

(1) Make reports on activity of specific students, i.e., what has Dries the Student done this semester, what responses have students made to a fill-in-the-textarea prompt. Views integration. Write plugins that will extract data from the serialized arrays (or JSON strings...) for custom data, make the data available to Views.

(2) Export data for analysis of student behavior, with custom programs in R, Python, or whatever. That means Views integration, and export to at least one external format. Since different log records will store different data, an export format that maintains data structure, like JSON or XML. Not CSV, probably.

Suggestions for module(s) to start with?