Hello: It might be a good next move to find someone with the right tools. For that drain valve, you want a basin wrench with a square shank and a big crescent wrench used on the basin wrench to remove the drain. For that gas valve, probably two crescent wrenches, squeezed together will loosen the nut.
Remember, this is gas. Get help if you need it. It winds up being a great way to learn plumbing… watch the plumber! 😎 Hot showers soon!