[fetchmail]I want to back up my IMAP folders

1. I don't understand what fetchmail does to a full IMAP folder tree. can 
someone help? i don't want my messages destroyed or deleted but simply copied.

2. I'd like to somehow back up my IMAP folders residing on my ISP's server. Can 
I get fetchmail to forward copies of my messages (old as well as new ones) 
through an SMTP server to another account...or something better? I don't run my 
own mail server.

3. can I run fetchmail on my Win32 machine in some form, although I do have 
Linux machine...?