I stand corrected. I was thinking of Latin hortatory subjunctives. (sorry for the pretension) http://en.wikipedia.org/wiki/Subjunctive_mood#Latin_and_the_Romance_languages I guess you don't use it for that purpose in German or English.
I don't know why no one believes me, but it is NOT a question. The word order would be the same if it were a question but that does not make it one. Imagine you are somewhere with a group of people and you say "Let's go home." That is the same thing and most certainly no question.