The important thing, it seems to me, is to be able to give the appearance of being "informal" while actually being quite formally prepared.
Yes, whatever you do, don't treat this as a genuinely informal conversation. Write out a talk, learn it, and then be able to go from minimal notes.
I was going to post a new question on this very topic, but searching the forums led me to this answer, which is brilliant, and exactly what I was looking for. I have an "informal" research presentation coming up in a field where not reading a paper means you're either unprepared or an intellectual lightweight, but I'll be speaking to a wider audience where some at least will see things exactly opposite. I've been wondering how to approach this for days. Now I know. I'm bumping up this thread because I bet I'm not the only one wondering the same thing right now.
