Hello, Jennifer!
You can view and download the files uploaded by your respondents by clicking into your “reports” tab, and then clicking on “Browse Reponses”. From here, you can click on any of the individual responses to view them, where you can download their uploaded files.
We're working on adding ni a mass-download feature, but its still in development. >_<
You can, essentially, combine your surveys through the question library. Click to add a question to your question library, then click to add that question from your library to your survey.