Ooops...I did mean Mike and Don in my earlier post. I even used the Back button to make sure I was referring to the correct graphics, but I guess my brain was playing tricks on me

I would have to second the idea of sticking to a single theme, ie, just Turtles images. If you go to
http://www.ninjaturtles.com and enter the art gallery, you'll find a bunch of graphics. Once I make the move to build my own cabinet, I'm going to vectorize a bunch of the images and use them.
But you could always use those additional images for Sideart. Theres some very good group images, and then you've got Foot soldiers, Shredder, the TMNT Logo, etc. So you can really mix and match and create a very cool Turtles themed cabinet if you'd like.
But I'd try to stick with one main theme. Or at most, do the control panel with one set of character images, and the cabinet sides with different images.
And for a Start, Pause, Player buttons...I'd really push that you add them to the control panel. They'll come in handy up there, and its going to be far more convenient to quickly reach up then have to open up the coin door and hit buttons.
If you dont want them on the top of the control panel, you could always put them in a different location. Maybe on the front edge, off on the sides like you would for pinball buttons. You can be creative...but I would still push you towards thinking about just putting the buttons on the top of the CP. If you check out the pictures of other cabinets, 99% of them all have the start buttons on the top and easily accesible, just because it works so well. So think about that before you complete the final design.