Can the Research Centers have multiple PIs, and can the PIs be from more than one university/institute?
Yes on both counts. Applicants may use the multiple-PI option, and the PIs can be located at different sites. If an application proposes multiple PIs, the leadership plan must address how leadership duties will be shared, and the application should follow the PHS 398 instructions at http://grants.nih.gov/grants/funding/phs398/phs398.html regarding Consortium/Contractual arrangements, such as including separate detailed budget pages for the sub-awards.