When Sololearn challenges you , are questions set to my experience/progress/knowledge?

Answer 1

It doesn't depend on your course completion/progress, you can get challenges from topics which you have not yet completed and some even are from outside the sololearn course as most of these quizzes are created by community only.

Answer 2

Yes and they are pretty easy at times. To be honest Soloearn just tries to let you win for some reason I do not know.