Currently Being ModeratedMay 1, 2013 1:24 PM (in response to Flemster)
If you're copying the photos into the library during import, i.e. a "managed" library,
you may delete the source photos uploaded to the Pictures folder. And yes, do it soon so you free up space on your hard drive. It's recommended that a minimum of 10 GB free space be maintained on the boot drive for optimal system and application performance. More if you use iDVD.
Faces can't be turned off. After its initial scan of your library just ignore it. Send a feature request for a way to turn it off to Apple via http://www.apple.com/feedback/iphoto.html.