I agree with you about the look of the frame. Wasn't that the point of COEs anyway? Shortest possible tractor for the most cargo capacity based on the length laws? I know long frames might ride better, but they just don't look right (to me anyway).
I have no idea what it is, but I have seen people using it in a similar manner to white glue. They use it for gluing in clear parts, and anywhere else white glue can be used.