what's the difference between enabled, disabled and hidden?

i want to know what's the difference with enabled, disabled and hidden?
also how do i stop people from answering the question twice?

Thanks

you can't vote twice...
and I think that:
enabled = everybody can vote and see the poll
disabled = nobody can vote but they can still see the poll
hidden = nodody can see the poll

is there a way to be able to export the results as a comma delimited or tab delimited file? I want to be able to download my results so that I can put them into a report.

Thanks