If the cameras are not broadcast units with a reference (Genlock) input, you will need to use a switcher with build-in frame syncs on the inputs. This will eliminate the need for synchronizing your cameras. As for matching, some switcher will offer a Processing Amp feature to match the cameras. Otherwise, you will need to spend some time matching the cameras through the controls on the cameras. Use the same white balance reference under the same lighting conditions for a start. The rest is tweaking the cameras until they match as well as possible.
E=MC2+/-2db