hmmm... its really hard to paraphase. Best is read multiple articles, make notes taking certain sentences from it. Then write your own.
I think that even if you post images from free sites, its curteous to mention the source. It's all about being supportive of other people's work, so they get recognized for what they do.
Incitentilly, almost all times in all of my articles, I list all the websites I used to get my basic research from, because those articles helped in shaping my view in the article. Doing this is decency.
Overall, its about sharing knowledge etc, I love sharing all my knowledge but no one generally is there who wants it(: he...he..he...
Having people interested in what you write is usually difficult, a process, and not every subject will appeal to everyone. But, little by little you generate and achieve someone who is interested.
Helping others to become known, that's important. They lend their images, or rather, they give them to the world, it's a good point, I think the best thing is to place the source, I think so.
Thanks for the comment @mintymile