As some one who does weding videos here are a few thots.
As far as a camera goes I would not use a low end camera (or soccer mom camera a I like to call them) you want something that wil give you compleate controle over the image (focus, gain, white ballance, exposure, etc) as well as easy control, if you always have to go into the menu system to change some thing insted of having a manusl option on the camera it self you could easy miss some thing important that might happen at the event. I use the Sony FX1 not only do i get great control but it is HDV which is something that might set you appart from other event videographers in your area. You might also need a video light for low light events.
Also a when youor customers see a niceer camera it gives them more confedence in you as a profesional.
As far as other plugins, you wont need any.
Also check out the Event Videographers forum here at the Cow