Hi,
Textures with poor details, shiny ones,... are a problem. Suits, wedding dresses... are not easy to scan. Sometimes it is better to tell people to bring a second outfit, just to have a backup. Also some markers ( like small post-its) attached onto the problematic areas helps. ( just needs a bit of photoshopping or mudboxing afterwards...) We are still in the development of a reliable noise projection ( laser technology), I will poost on this forum if we succeed :-)). Nothing against Photoscan it is a fantastic tool, but have you tried Autodesk recap, for some scans ( esp. mesh building) it works better.
Regarding camera positions, for a multicam rig (360 array of cameras) you can use the camera position tool (xml file).
Good luck, all the best Andreas