Since I didn't have "bIQIp" as a choice I chose "SuQIp" and was graded correctly. So is "SuQIp" referring to 'you' as plural?
That's right. *You (plural) are stupid."
I accidentally wrote bIqIp, and it was counted correct. Aren't q and Q different letters?
They are and Duolingo almost always treats then as different, but there are still a few places where Duolingo gets confused.