What's the use of the POLL_MD5 field? I am trying to add polls directly to the database.

As far as I can see, the MD5 is a hash of the user displayname and time. Something semi-random. It is really used somewhere? When adding a poll with 0 in the POLL_MD5 field it works fine too.

It's used to track the poll during the process of using the poll manager and posting, once posted it basically isn't used. So if you're manually adding a poll then you don't need to worry about it.

ok, great. Same thing for the file md5's?

Yep, same thing there.