Considering point 1, I’m disappointed that so many amateur photographers don’t want to share their pictures and at the same time I’m glad that a few thousand do. So when that small of group of people that is kind enough to share their work gets ripped of, I tend to regret that more than when people rip off the hoarders.

1. “The most common mistakes are 1, using pictures that are not licensed under Creative Commons and 2, not giving the photographer credit for his or hers picture. The latter is worse”

I’d have to disagree on not providing credit being worse than taking pictures which do not have a CC-license. Both are bad, the first to me is worse.

2. Under crediting, you say: “The best way to do this is linking to the photo page. Some photographers want you to mention their name as well.”. Actually, the CC licenses specify that you always (when it’s provided) have to mention their name / pseudonym. See this part of the never-read actual license (not the ‘human-readable’ one):

“You must keep intact all copyright notices for the Work and give the Original Author credit reasonable to the medium or means You are utilizing by conveying the name (or pseudonym if applicable) of the Original Author if supplied; the title of the Work if supplied; to the extent reasonably practicable, the Uniform Resource Identifier, if any, that Licensor specifies to be associated with the Work, unless such URI does not refer to the copyright notice or licensing information for the Work”