I tried to contact some media sites a month ago because I was creating that service. No one even replied my email. I do not think they are even interested in it.
I think it is really hard to know when you should optimize and when not to. Most of the time a prefer to design my code in such a way that is not fully optimized but it can be with a few tweaks. There are many places that might not be needed and it has no sense in optimizing.
1. It depends, you can make something quickly but when it comes debuging or make strange things you need a deep understanding of what is going on. I would say between 30 to 40 hours.
2. At first it's like 2.5, but when strange things start happening, it can slow to about 2.
3. I would say 2.4
4. It was really popular, has a lot of resources available and made development really easy.
Now for my personal projects I'm learning ReactJS
1. The framework is really easy, and it can take about 10 hours to learn it deeply. The difficult part is thinking the way they propose you with Flux. That can be as long as angular with 30 o 40 hours.
2. Productivity can be a little worse than angular with 2.0, but results are much better.
3. This is the best part. Although I haven't build a big project, at first sight it might seem this is the best part of react. I give it 3.0
4. Speed, control of what is going on in the views, popularity, the idea of having the possibility to easily port my apps to native with React Native, the tools such as browserify make even better.