Uploading supplements in college portals

So a good number of schools I applied to have additional supplement boxes like these http://gyazo.com/70728329706aeaeb098d9d15efc8ca88 on their applicant portals. My question is, what can I upload here? I was planning to upload a research abstract for sure, but can I submit a letter of recommendation from the people I did research with too? Is this where I would let colleges know about updates (awards, affirmation of interest, etc)?

The general rule of thumb is that redundant additions are unnecessary, and can actually hurt your chances. (ei same LORs). Research abstract is a great idea.