Nie, dziękuję. Mam już samochód.
Could I add a "czy" at the beginning and still be correct?
Yes, any Yes/No question will be correct if you start with 'czy'.
Is konia the accusative of kon? Thanks
It is as well, but here it is Genitive, as needed by "potrzebować".
Dude, choose 2 answers
There must be a mistake with this as i cannot progress despite choosing any of the 3 answers.
I would give my kingdom for one.
Konia! Konia! Królestwo za konia!
("za" + Genitive to mean "for a horse", and I'd say that it's "Konia!" on its own first because it implies "Potrzebuję konia" = "I need a horse").
I used "wy" with the interrogative "czy" and got an error message. Why would not "wy" be acceptable?
"Czy wy potrzebujecie konia?" is accepted, it should have worked.