Kevin - I can't really speak about the Mac, but yes, Mavericks is now supported for PT11.
YES you will need the stand alone editor if you are using PT 11, HOWEVER, PT 11 is a combo license that also comes with PT 10, which still uses the internal editor. You can install BOTH PT 11 and PT 10 on the same machine, but you can only use one at a time, which is really handy if you have a lot of older plugins.
I am on a PC and have never had the issue with stand alone editor but some have. It mainly appears to be going off screen, but as I have not had the issue, I don't really know.
PT11 has a MUCH better memory manager, and actually gave my older machines a little longer lease on life. I am getting better performance with 11 so I put off upgrading hardware for another couple years, which is a good thing, because studio revenue is off a little so far this year.
Yes I like buying from SW BECAUSE they extend the warranty, but luckily I have never needed to use it.
Let us know what Tone Dr has to say and the cost if you will, Id be really interested to know what the issue is.
Good luck my friend.