Strong disagree. Expertise often looks easy. He had to understand the rules on a fundamental level before he could break them as he did, to express not just pictures but the underlying form and composition.
In my opinion it is harder to paint abstracts like Picasso did than it is to paint realistically.
I agree with this. It's harder because you have to have all the technique before you start picking and choosing what to leave out. An abstract painting becomes at least in part a story of what the painter decided to try, some unique combination of choices, at several levels of zoom. This is dangerous stuff because its easy to alienate a viewer this way. But done well you find a (substantially) new path to beauty and wonder.
No. Could a child paint something that to their own parent seems similar? Maybe.
Children's art usually has a freshness, originality, and vibrancy that's missing from highly skilled adult art.
I had to get over my worship of realism before I could appreciate it, though, and I find it very sad that most non-artists are still stuck at valuing art only by how realistic it looks.