Students really do treat you like a professional if you talk like one!
It sounds like the experience went well, all in all. Don't fret about what you forgot to mention to the students. Their attentions usually wander after about 20 minutes. (Not even kidding!) I've been doing different things in my classes because of that. Like I talk at them for a few minutes at the beginning of class. Next, I start asking THEM questions. After 15-20 minutes, I break them into groups for a 10-minute group activity. Then, we have a large group discussion about what each group discovered. Works much better and I don't have anyone falling asleep at their desks anymore! Long story even longer, I've discovered that I haven't told them everything I know. Oh well. The process works. They can pick up more knowledge along the way. I can't teach 'em everything!
I'm pleased you had an opportunity for this practice run. I hope it was what you needed to build up some confidence!