Hi Brett,
The .rppkg files are the files inside a .rp file which is essentially a zip file. I think when you're downloading the files, they are being saved as .zip. If you rename to .rp that should let you open them.
There isn't a "built-in" way to create the loop and make it interruptable but Jeff's example in this thread "interruptible loop.rp" shows a clever way to do loops with OnFocus events and make them interruptible.
However, in your example, without making the loop repeat, you may be able to just show the Popular panel and bring that to the front, but in the popular panel states put a background rectangle to basically cover up the random panel that may still be animating beneath it.
Then, on the click of the Random button, you can show the random panel again. At that point, you could also include the actions that animate through (the same as in the OnPageLoad). But if you've set that up to be a perpetual loop using the OnFocus method that Jeff uses, I believe you can just set the panel state to the first state and put the focus on the "Next" textbox and it will continue to loop from that panel state.