Zurvival: Do not change your name until you have logged in once after it comes back up in 1.8. Logging in will allow the updated plugins to correctly associate your account UUID with that name, and then again for the new name when you later login with that, thus keeping everything associated with you.
LVS: Changing your name will cause you to lose your stats/ranks, as these are stored associated with names and not your UUID. See https://bugs.mojang.com/browse/MC-77229 to follow this issue, hopefully Mojang will have a fix for this. Until then, you may need to re-earn your Zedling rank following a name-change. A Guardian may help you out, but it is also a bit of work looking up your UUID and past names manually and is something we are not yet set up to do; so don't count on it. Zesty/Zriends will have their ranks returned to them, just send me a PM on the forums
Sorry for the hassle, hope you get the names you want ^_^
If you'd like to know more about this fabled name changing, you can read all about it on Mojang's blog: https://mojang.com/2015/01/announcing-minecraft-name-changes/