IIRC, two ways to inspect the orbiter's underside were developed - an inspection boom that could be attached to the end of the arm equipped with sensors (visual and laser), and a maneuver procedure before docking with the ISS - the orbiter would make a full rotation allowing it to be photographed from the ISS. During one of the first post-Columbia flights, a problem - a spacer which protruded from its proper position between two tiles was removed during an EVA. This rotation maneuver was the most shocking to me - as it showed it never occur to anyone just to rotate the shuttle so it could be inspected with a pair of binoculars. Such an inspection could be conducted as early as STS-63.

In a sense, every shuttle was an X-plane - it was as much a research vehicle as a commercial transport to LEO. One builds shuttles to learn how to better build shuttles and, in order to do that, learn as much as possible.

BTW, I envy you (in a good way, of course) more than a little. Working for NASA is a really cool thing.