Don't worry about vision when selecting the processor since by then you'll know what you need to know (vision is beyond most of the "hobby" microcontrollers out there). And when you add it, it'll probably be a dedicated processor anyways so don't worry about finding a control board with everything else you need as well as vision.
For someone whos never played with this stuff before, it was still very easy to get up and going. I mounted it to a base I purchased for cheap off of Pololu (Ill try and post some pics). It doesnt do much right now, just follows commands from my computer over the serial port -- but I have some ideas