1) A whole blog is dedicated to demonstrate forensically that Comet C-P is a single body that has stretched :http://scute1133site.wordpress.com/
This is important to end the rot of speculation about ablation and contact binaries.
2) considerable rotation rate change from differential outgassing over a comet year.
This makes more plausible the centrifugal forces required to stretch the comet over time.
3) the lack of proportionality between surface insolation/temperature and outgassing. This indicates other complex sources of energy other than conduction from the surface.
4) Solid look and feel exterior, but with a very low density interior. Lots of room inside for gas chambers and conduits.
5) an eclectic mix of higher molecular weight gases detected than expected. Again pointing to complex process and energy source.