I posted quite a bit in Palmor's thread and you can read that stuff already. We can overload you with advice and that's fine, use what you can and discard the rest.
One thing I feel for you is the times. a 5PM wedding and a 6:30 reception? How the heck are you going to get any personal shots? People don't realize it takes time to go to a location with the couple and take some of those "signature" shots everyone wants in their albums. You can't do that in 36 minutes. I usually ask for 3 hours. trying to pull them away from the reception is nearly impossible most of the time.
So advice:
1) look at wedding shots on the web. Copy ones you think will be appropriate for their day. Print them and put them in a small booklette form that can fit in a pocket. These will serve as a "checklist" of reminders. You'll have lots of great shots in your head Saturday morning and forget them all Saturday afternoon. Plus if you want them to pose a certain way, you can show them a smaple and then they know what you want.
2) Flash. Any recent model will do. I do manual flash shooting all the time. But you dont have the time to get enough practice for that. So get the AF360FGZ. It will do the job just fine. I use a $2.00 DIY flash diffuser to soften the light. See
here how to make one. Practice with this a lot before the big day.
3) Get Sanyo Eneloops batteries or Rayovac Hybrids. No other battery will do. Period.