2 a) The meaning of “by-nc-sa” :
The “by” part refers to crediting the author of the media used.
Nc means that you cant use the picture to gain money from it.
Sa is the abbreviation for “Share Alike” meaning that if you share the picture, you must have it under the same or similar copyright licence as the original.
2 b) http://photobucket.com/ is another site that has free to use photos.
4) The answer for the question “Am I free to copy facts and ideas?” is:
Yes. You are free to report the facts and ideas embodied in another person’s article or web page. Copyright only protects the expression — the combination of words and structure that expresses the factual information — not the facts themselves.
This means that you can repeat facts and ideas in your own work as long as its put into different wording as the original.