The laws differ depending on what country you live in. If you are downloading copyrighted materials in Canada for instance, you are not in any danger. However, in the US you are. Fair use is an extremely gray area as you can read here. Here is another link that may be of interest as well. You are also encouraged to visit our sister site Euro-Copyrights.
I can tell you one thing, someone correct me if I am wrong, but there is no way fair rights will "protect you" if you upload copyrighted materials without prior consent from the copyright holder, anywhere in the world, that I am aware of.
No it is not legal to download copyrighted music even if you own it already in the US. Again, it all depends where you live.