Love your ideas! Thank you very much!Welcome to the org:wave:
Enjoy modding your beetle. As Chuckie said, be yourself & unique. Suggestions are like eating fresh fish- eat the meat & spit out the bones. Glean what you can and take the other suggestions as just that.
Our bugs are life-sized model kits. With a Bentley manual (a Haynes wouldn't hurt either), You can getter dun. There's many good threads posted here that'll help you out a ton too. Frank/D2Beetle does great DIY threads and they can pretty much walk you through your project.
Can't go wrong with the Herbie motif- it's classic and a hit with the kids and kids at heart.
Your interior mods can range from mild to wild. Yes, seat covers will spruce it up for sure. I concur that Wet Okie makes a good seat cover. Katskins are top-notch, but they'll take more cash out of your coffee can. You can even spruce up your seat covers with having a shop embroiderer put "53" on the seat covers.
There's many places on the interior where you can place the "53" and or the red and blue striping. Places like the center dash. top portion of the doors, reupholster the door cards with "53" embroidering.
Your headliner is a very creative palette as well. Many folk, such as myself, have used fabric to replace the headliner fabric. Many have chosen an assortment of patterns to jazz things up. I went plain-jane and went with black tweed. If there was a fabric with the VW logo on it, that would be cool. The options are endless.
I will suggest going Indiana Jones and search through the threads, and get some inspiration.