I'm a little concerned about upgrading to Mountain Lion right now because I'm not sure how some of the data I have on my machine will get shoehorned into Mountain Lion's new apps and features.

* Does "Notes" start out clean? Does it import your To-Dos from Mail (the way Notes would sync before iOS 6/ML)? Or does it import notes from Stickies?
* What happens to all of my Reminders in iCal? Do they automatically get imported into the Reminders app? Will I end up with duplicate Reminders resultant from iCloud issues?
* I have the iChat setting turned on that saves all your chat logs. Will I still be able to open them in Messages? Will my iMessage conversations start to get saved in the same logs? (Is chat logging even still in the Messages app?)
* I know Gatekeeper is enabled automatically, so what happens to always-running processes that I have set to start when my Mac turns on? I don't know if apps like Dropbox, LogMeIn, f.lux, or any of the others that start up as soon as I boot my machine, are signed with an Apple Developer ID, so will this cause big issues when I update and all of these unsigned apps try to run at once? (I plan to disable Gatekeeper minutes after upgrading, but I don't want it to cause issues that might keep my machine from booting up at all.)