On your #3, I prefer mjd's advice to "get to the point". They have already chosen to sit in your talk. Hopefully they know something about who you are, what the talk is supposed to be about, and there is little point in wasting the period when you are most likely to actually have their attention on reminding them of that.

(Note, mjd is the author of the conference presentation judo talk that I linked to above. TPC is The Perl Conference is the predecessor of OSCON. I don't know if he has continued to maintain the top speaker rating that he had, but he did so for a long time. He is worth listening to.)