I need few suggestions.

I am intending to install the preview as it will be better than windows 8. I had purchased windows 8 Pro from MS store and also installed the media center.

I will create a system image. download and install 8.1 preview. when RTM is available I will restore from the image and install the final version(prevents me from re installation of application). Is that okay?

Does the preview / RTM require a new key or will it work with the current key installed?