Unfortunately not Snacktime - the list would be extremely long. However, browsing spells in-game is quite easy and probably quicker than a changelog anyway.
Items are easily viewable using Momfreek's excellent browser:
http://dom3-mod-inspector.googlecode...?mod=CB1.92.dm . Also there's the PDF packaged with CBM 1.92.
Units: I'm afraid there's no easy way, sorry. The best thing is to quickly test out your strategies in single player games.