Sadly in India as of now you'll find more companies looking for Angular developers. No of (Angular + RoR + Django) postings / no of React postings is like 20+ . And because of less demand for react, you'll be easily paid less than what you are worth in case you go react path as of now. Can't predict what'll happen in next 1-2 years.

a.slice() is the most performant one as I read long back in SO & everyone mentioned same here. I use that.

None, just a lonely room & issue/goal tracker.