The scallops are cut using a scallop blade in a rotary trimmer. This is the fastest and easiest way you'll ever find to put a border on paper. If better cuts in thicker paper don't appeal to you, this might be a good reason to upgrade to a rotary trimmer if you are still using a pull type blade.
I couldn't find any coordinating paper that matched the markers. I thought I had some but it didn't work for me after I finished the image. So what was I to do? Make my own of course using stamps. It didn't translate well to the smaller blog image but if you look at the larger image on the website (by clicking on the image) you can see I stamped an XO image with a bandaid type pattern in versamark on the paper. Versamark is very useful for doing this because its clear and the paper simply becomes a darker shade of itself once it dries.