Welcome to the site. I hope you enjoy your time here.
For scripts and variables, only use them when you've figured out you need them. Until you need them, forcing them into a story will make the story bad. When you're trying to do something with the story that requires them, then you can explore how to use them.
As for the preview, you could click on your name and that will take you to your profile and your games are listed there. Clicking on a story name will let you preview it. Or you can go to My Stuff - Storygames and see a list of your games there. Clicking on a story name will let you preview it.