Yes, you can uninstall 2012 and then install 2013 first.

As long as you change the path variable, Emacs will find it. The path variable can be found by:

 1. right clicking my computer 2. going to properties 3. then advanced system settings 4. and in the systems properties window go to environmental variables 

Once there, you will a systems variables box with a scroll bar and this is where you can set and change path variables in Windows.

Yes, you can uninstall 2012 and then install 2013 first.

As long as you change the path variable, Emacs will find it. The path variable can be found by:

 1. right clicking my computer 2. going to properties 3. then advanced system settings 4. and in the systems properties window go to environmental variables 

Once there, you will see a systems variables box with a scroll bar and this is where you can set and change path variables in Windows.

I don't use Windows so I have not idea what you would change the variable too but that is where you will find it. Also, I am not sure what it will be called but it should be obviously related to TeXLive.

Yes, you can uninstall 2012 and then install 2013 first.

As long as you change the path variable, Emacs will find it. The path variable can be found by:

 1. right clicking my computer 2. going to properties 3. then advanced system settings 4. and in the systems properties window go to environmental variables 

Once there, you will a systems variables box with a scroll bar and this is where you can set and change path variables in Windows.

Yes, you can uninstall 2012 and then install 2013 first.

As long as you change the path variable, Emacs will find it. The path variable can be found by:

 1. right clicking my computer   2. going to properties   3. then advanced system settings   4. and in the systems properties window go to environmental variables 

Once there, you will a systems variables box with a scroll bar and this is where you can set and change path variables in Windows.