If you are on a family computer where you are really the only person who plays the game and don't really have anyone in your household to hide anything from you don't need to clear the saved emails whenever you exit the client or game.
Now keep me logged in and save email address this also will depend if you are playing wow on a system that you do not own which I think it doesn't take to much thought to rule out never leave yourself logged into a system that you do not own.
Problems with I've heard several people having problems with while trying to play Wo W on a linux based OS with Wine HG (yes, you can play mist of pandaria BETA with Wine HG on linux, like Ubuntu, Debian, Fedora and so on).
I can understand that But in fact it appeared without even having to reinstall the game.
My box was on accept_keyword amd64, and I switched to ~amd64.
To fix this issue, open winecfg (type "winecfg" in a terminal), and on the Libraries tab, enter "msvcp140", then click "Add". Program: C:\Program Files\World of Warcraft\Wow-64Process ID: 57 Exception: 0x C0000005 (ACCESS_VIOLATION) at 0000000005A11A71 The instruction at "0x0000000005A11A71" referenced memory at "0x00007F38ACD6C028". you'll need to force World of Warcraft to use the 32bit client.
If you use to launch the game (that's only possible if you don't use Open GL, see below), you can change Wo W to use the 32bit client from the settings available via left-click on the blue icon on the top-left corner - the menu is not responsive and unfortunately you have to click quite a few times to get it to work.