Thank you for adopting this rabbit!
The gurgling is most likely due to him adjusting to changes in his diet. You can give baby simethicone gas drops, 0.5-1 ml every hour for 3 hours and see if that helps. Simethicone is not absorbed by the body, it just acts locally in the GI tract and gets pooped out. Many of us bun owners use it as a first measure when a bun displays symptoms that could be related to gas.
A bun that lies down with his eyes half open and his legs behind him is usually a content and relaxed rabbit. If a bunny sits up in a hunched position and looks uncomfortable, refuses to eat and tries tio hide away or refuses to move at all, it’s cause for concern. You can do the “treat test” – offer a treat, if the bun takes it and eats its without hesitation, he’s most likely just resting. Most rabbits rest during the day. They can very well sleep in a bunny loaf position with their eyes open, it’s perfectly normal for a bun but can look uncomfortable to us humans.
What type of wood do you think the bench is made of? Many types of woods are fine for rabbits to chew on, provided they don’t eat really large amounts of it. Because wood is hard they often don’t eat a lot of it per day, but it’s good to keep an eye. Buns often like to sit/lie under benches, chairs or foot stools, because the “roof” protects them from attacks from above, from for example birds of prey.
It’s good if you can get him to eat more hay. Sometimes you have to try various hays before you find one that your bun will like.