Hi. This thread will help you with most of your questions.
http://forum.ppcgeeks.com/showthread...t=personalizer
Once you have replaced all the files you want to change, yes...zip the files.
You then need to simply change the extension of the file from (for example) theme.zip to theme.theme
What I do is open the zip file, then in the winrar or zip wondow, go back til I see the file with the extension showing. Then delete .zip to .theme, and there ya go.