Sometimes I go through and hunt and pick things to reset, but I wanted to reset everything. Will this cause any major failures?
Hard to say without knowing everything you have Why not make a backup of the folder first in case you need to restore something
Most programs will automatically just make new plist files, but some might behave unpredictably. You might consider just making a new account instead, too....
So I trashed every single file and folder in the preferences folder, rebooted the MacBook and everything was reset. Everything. I had to re-enter some passwords and get through some obligatory install menus, but that's all. One thing to note, it cured some problems I had with my MacBook. Previously, it took a full minute to go to sleep and I thought it was a hardware problembut now it goes to sleep and wakes up instantly. So cool. I'm sure it fixed some other stuff as well.