I wouldn't worry about the acidty of your soil. You're probably fine there. Most plants like a range of pH from 5 to 7, and your soil most likely fits into that category just fine. Dig a hole that's about twice the size of the root ball you're going to stick there, loosening the soil to make root growth a bit easier for your new plant, and make sure it gets enough water. You can mix some compost or soil into that if you want but it's not really necessary unless you have hard packed clay heavy soil. Throw some compost on top like once per year (spring) and you'll be fine.
Herbs are a great way to begin. Most are very easy, and you get extremely quick edible results. Berries are my second suggestion. Strawberries are super easy, and if you get a big patch of them you can go outside with a bowl every week and have your fill of strawberries.
Blueberries are another good one, and do well in containers. But they are not self-seeding. You need two DIFFERENT cultivars planted close by in order to get fruit. Every plant in a cultivar is genetically identical, and the plants will "know" if the pollen is genetically theirs. Also, catnip is a type of mint, so it spreads like lice in kindergarten. It will take over any space you put it in, so be aware of that if you put it outside. (I would really suggest a pot. I put peppermint in my garden once to deter fire ants, and it literally choked out every other plant I had in that space within a year.) Strawberries will also spread, but are self-seeding so you only need one cultivar. They're also perennial, and will come back every year, even if it freezes.
Wow! You have quite the arsenal of soil amendments! I can't say I use any of that. I make compost at home with kitchen scraps, grass clippings, and oak leaves. Worm castings, though, I know make wonderful fertilizer.
