Answer 1

Well, the history part of the Wiki article can help answer that

https://en.m.wikipedia.org/wiki/SoloLearn

Answer 2

The hardest question xD

Answer 3

No idea. In any case, in the first articles about Sololearn you can get an idea how long the company has:

https://www.sololearn.com/Blog/4/mobile-learning-platform-sololearn-raises-100k/...

Answer 4

in 2014

Answer 5

sololearn is made about 4 years ago i think, but its never too late to learn coding, because it will help you with more than only code-writing