I'm assuming since you say "included" mike you have a camera with an xlr input. I have a number of Rode microphones and rely on them. I would much prefer the Rode over the Sony.
I've never shot a wedding but have worked as a soundie on videos and a camera operator on movies. I was just testing the Rode nt4 stereo mike on a boom pole with the new 32 bit zoom f3 recorder for sound effect recording. Lightweight and impressive quality. Frees me from the sound bag.
Curtis Judd has a great YouTube channel. I think you'd find it a very helpful resource for sound.
More information on what your camera you're using and how you're working might get more responses. Wedding photography is specialized and I'm sure there are wedding photographers on these forums who would be glad to help.
