I wish to upgrade to WP 3.0,
1) But where to get:
Plus, How to determine FTP / FTPS (SSL)?
2) How to I install my own wordpress theme?
You're using the preinstalled Apps system. Only DreamHost Support can perform this upgrade, as it will apply to all users. Same goes for themes. If you want full control over your WordPress installation, you'll have to install it as an Advanced One-Click installation on a Fully Hosted domain.