So here’s the deal. Avoid EBay, you’ll pay waaaaay too much. I’m scared to ask how much you paid for that bike, but what’s done is done. You should have done research before you bought it, but here we are, so let’s make the best of it. There is lots of info on this site about de-rusting a tank, and getting it running. Spend a day or two searching and reading all over this site, especially the wiki tab. You’ll find everything you need to know if you look for it. Read Fred’s guide.
Second, don’t pay a “tech” to deregulate as you say. Don’t hire a mechanic as they likely know nothing about these little bikes and will probably screw it up worse for you. Learn to fix it yourself, there’s no other good option, period. Everything you need to know about de-restricting your moped is on this site. All you can imagine about modifying and making it faster is on this site, if you poke around a bit.
Third, those plastic pieces you speak of did not come on your model. They only came on the Deluxe (silver colored) version, not on the standard (red), or the hard tail version (blue). They will fit on yours, but they are impossible to find, so bag that idea.
All that said, nice bike. In my opinion, the Free Spirit is about the best step thru moped you can own. I have two of em. Reliable, strong, and cheap & easy to work on. Nice bike; enjoy. And have fun reading and learning.