Can you mix "traditional" vSCSI mapping and pass-thru (NPIV) on the same adapter (5735) for both Disk and Tape? Can you SAN boot a VIOS from the 5735 adapter?

Yes, mapping both vSCSI and NPIV on the same adapter is supported. Further with proper zoning, it is possible to SAN boot the VIOS with the same host bus adapter that is servicing the NPIV traffic. The VIOS would need to be running before the NPIV-based traffic can serve the clients. Use care with this configuration because even a simple error in zoning could disable a VIOS and result in loss of the services it provides.