15 seconds max otherwise you get oblong stars. 6400 iso will capture the quick flash of the meteor. I'd go with the 10-20mm. It may depend how tight they are as they come in, something longer like the 35mm would work in that case. Last time I used the 18-55 at 18mm and it was wide enough. It was f3.5. Tonight I'm using my 12-24.
Remember that the meteor will appear for half a second or less, and you need to have the iso high enough to capture it. I found a lower iso didn't get enough of the meteor light and resulted in a very thin line. If you go for a shorter exposure, 5 seconds or so the stars will be less bright but the meteor will be bright. Depends how busy it is, 5 seconds will require lots of shots to capture anything.
We are looking at some cloud tonight, better tomorrow night. I'm going out to see.
This was two years ago with the K5 in August.