1. - See http://codex.wordpress.org/Resetting_Your_Password
2. - As often as you like, it's your WordPress installation and no one elses.
3. - Also up to you, see item 2.
4. - Nope! This is the staffed by volunteers support forum for self-hosted do-it-yourself WordPress.ORG software installations. There is no phone (or email) support.
Edited with correct links
Edit: If you have a WordPress.COM installation (your profile link indicates otherwise) then you can ask at http://en.support.wordpress.com/
For the differences between the two see this link.