Why is tanssitko sinä? Do you dance? And Tanssvatko he? Are they dancing?
Could "tanssitko sinä?" Also be "are you dancing?"
Yes, in both cases the Finnish question can be translated as either "do you/they dance (in general)" or "are you/they dancing (right now)".
Does this also me "Are you dancing?" (You as in singular)
As stated above, yes it does.
Are you dancing is also one of the accepted replies here.
Wish i would not loose hearts for words never given to me before
Yess, that happens all the time