Kinetics and thermodynamics is essential as far as theory goes, calculations a little less so. The best stuff to know if you really want to understand o-chem at a deaper level is the molecular orbital theory, HOMO LUMO stuff, and as much intro p-chem stuff they feed you in gen chem which is either a little or a lot depending on your prof/institution. Though there is not much that is really requisite for orgo, you will remember things better, not have to resort to rote memorization, and perhaps even enjoy the course if you understand it on a deeper level. Probably help with the 'cats as well. goodluck.
-jot