Changelog?

I don't think theres one around(I assume not since some sites have been keeping one)

Is there a plan to keep one? Not neccessarily for everything but if I go running into battle with a spell that worked fine the day before and now does half the damage or whatever it might be helpful

Or now that the full game is about to be released will they stop tweaking numbers on spells and instead add new ones with new quests and so on and so forth?

balancing is an ongoing issue. a few new skills are possible, but most new skills will be implemented in expansions.
as for changelogs, you must remember that this game is based on streaming technology. the client is updated very regularly, up to several times a day during BWEs, as well as in-game updates are being streamed live all the time. there were no changelogs during BWEs but as things may slow down a little for retail, it may be a possiblity.

A bit off topic, but it is no longer a matter of how much patching is done, it's more about how much builds are done, since those require you to relog.