The best source for info is Fewmiles unofficial Oneworld website. he has pages dedicated to the topic with prices for most of the countries in the world. I don't know the URL off hand, but a typing unofficial oneworld into google will bring it up.

I do not know about using miles for a rtw trip other than that it is possbile. It has been discussed before on this board, so do a search and see what comes-up.