2 - If you're not sure about what you're doing, just don't do it. I don't want to be responsible because you crashed your computer in some way because you wasted your registry.
3 - If you don't have the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\ directory, you can download and apply this file to your registry.
4 - Windows Vista users might want to check this post too.
Basically, this fix is deactivating the Nagle algorithm to improve your ping. If you don't want to do it you can just wait for the 2.3.2 patch as it's supposed to deactivate it too, but I don't think you can test it on PTRs right now because the updated patch notes from the latest PTR Build (7705) are actually for the upcoming build (7710).
Quote from: Hortus (Source)
The patch notes that were included with this build (7705) are actually for the next build (7710).
Once you're done with the technical stuff (it probably won't take more than 1 minute if you're not too bad), you can finally get your reward.
Even if in this case, the fix was used to decrease a very high ping, it seems to work very well on low (~100ms) ping for some people (lowered to ~20 or ~30ms).
——我修改了这两个注册表值，似乎对我的机器没有什么影响（浏览/下载），但我不保证这些方法一定没有有副作用！所以假如你对电脑一窍不通，请在高手陪同下进行这些修改！同时，我没有WOW程序，无法验证是否能够降低ping值，请大家自己尝试。