1. You will need about 8 scans around the head and one from above. Have a look to our User Gallery and you will find some examples. E.g. this turn around scanner:viewtopic.php?f=2&t=3415&start=15
Artisan S is right, don't try to scan a „living head" with a laser. It's possible but each scan needs a lot of time during the person must hold still. And yes, laser light could be dangerous for opened eyes. I have realized that a person can hold its eyes open without „pain“ if the light intensity is not more than 200 lumens from a projector.
Some time ago when structured light scanning was not yet possible with DAVID we had laser scanned (only) faces with closed eyes, e.g. here:viewtopic.php?f=7&t=451&p=2452&hilit
2. In DAVID's Shape Fusion it's relative easy to stitch the single scans.
4. The texture will automatically be captured for each scan just after the scan. In general it's difficult to scan hair, best is to spray it white before. Or do it like Artisan S it suggested.
5. Total darkness isn't necessary, dim the room light.
6. The resolution depends on the used camera and projector.