most (not all, some contributions are QTVR-only due to historical reasons)
many, but depends on photographer's choice of file upload (newer event = more likely to work) and your device's capabilities. You may experience slow playback, distorted images or unexpected browser quitting if there is only limited memory/GPU power available.
Sustenance to me is the basic things of life and what can be more important than H O M E with all the things present to sustain every part of the body. While food is important one must not forget the sustenance of the mind present in books, music, scenery and of course not forgetting the modern tools of digital camera and computer and last but not least friends and family: and of course one's spouse.