The best beginner fish for that tank is a moorish idol!
Just kidding DON'T DO THAT!
If you want a good beginner coral, go with some zoas! Always my recommendation. They can be so colourful and bright, and are usually very easy to keep (there are a bunch that will die because they just want to)
Also anther good beginner coral is mushrooms. There are lots of nice ones!, some have striking patterns, some are just a single deep rich red or blue, and some are colourless, but with big orange bubbles. If you can imagine a mushroom, chances are somewhere in the world there is one just like it.
My motto is "If you don't love it, don't get it!" If you stock your tank with only the corals you love at first sight, you will build the perfect reef. "Perfect" because it makes you smile every day.
Or if you're not that into corals, same goes for fish! You have even less space for fish, so make the best of it!
But, I'm not telling you h2w your tank has to be, enjoy the hobby the way you want

Your tank is not that large, but whether you should still get a protein skimmer depends on how much fish you want, what fish you want, and what corals you want.
SPS tank? Get a skimmer. Softie tank? Carbon filter is just fine. One fish, not that much waste, 7 fish, lots of waste.
Anyway, welcome to the hobby, and to R2R! Good luck with your aquarium
