I bought the Pentax AF-540FGZ, their top of the line. I was hoping for perfect compatibility, which I got, and to avoid knowing anything about flash except put the camera in P mode and let the expensive electronics make a perfect shot. That didn't work for me. So I don't think you can avoid knowing anything about flash. In the short time you have and the production-type environment of a wedding, I'd suggest something like it, with P-TTL, tilt, swivel and lots of power. But you will also need some experience to get the best out of it.
The main problem that I see for you is the wedding requirements force you in a direction that may not make sense for other photography, just to cover all possibilites at one event.
I was only partly kidding about a beach wedding in Hawai'i. It would solve all your problems. I took this shot with a Pentax *ist DS, Super-Multi-Coated Takumar 135mm f3.5 probably wide open, at Anini Beach on Kaua'i. But I didn't have to be the main photographer.