For the first blank, the clue is offhand remarks, so the blank means something like “offhand.” Glib, which means “superficial or showing a lack of concern,” is the closest match for this. Sticking to prepared talking points can result in a lack of “excitement” or “naturalness,” which spontaneity matches. For the last blank, you know the crowd’s responses are lukewarm, so the answer for that blank is tepid.