<p>Does anyone have any strategies/tips/traps for moving to Team System? Should it be done in baby steps, or all at once? Should we migrate our SourceSafe library over, or draw a line in the sand and move forward? Is it worth brining SharePoint into the mix? Any thoughts are appreciated.</p>

I've never had to migrate to TFS, but have used it pretty extensively for the past couple of years.
Regarding your question on Sharepoint, we've found it pretty useful in conjunction with TFS. We use it primarily for documentation management and for storing other "non-technical" artifacts related to the project. Some dev teams advocate keeping documentation in source control alongside source code, which is OK, but in my experience our project stakeholders have an easier time accessing relevent project documentation via the Sharepoint portal than they would having to interface with source control.
I basically was able to distribute the URL to the sharepoint site associated with our TFS team project to the concerned non-technical team members and have been able to avoid constantly e-mailing documents around, so it's been great for us.