Definitely scan them. You can do much more with Pan/Crop than you could ever do with a video camera (unless you have a computer controlled motorized head, that is).
If you don’t want to do any zooming in, set your scanner to 150 dpi.
My rule of thumb is 1″ = 100 pixels so a 5″ x 3″ image would be 750 pixels x 450 pixels which is close enough to video resolution of 720 x 480.
If you want to do some zooming in on an image, figure out how much and set your scanner accordingly.
As far as 4:3 or 16:9, it’s a simple function of matching the image’s aspect ratio to the project setting. This is a right-click option in the Pan/Crop window or can be done with a script