I’m glad you’re taking the time to read up on it! Like you, I’ve also noticed a lot of descripencies in lists of what bunnies can eat online. I would agree with Osprey’s suggestion to check rabbit.org, since they are very reliable.
As far as veggies go – the most popular choices at my house: dandelion greens, flat leaf parsley, dill, cilantro, basil, spring mix and about once a week kale. I generally just avoid things like brocolli and cabbage since it can cause gas and tummy upset. Kale needs to be only once a week since it is high in calcium.
I would avoid all processed things like cookies. All treats should be really limited. Bunnies have very delicate balance of flora and fauna in their tummies and it’s really important not to give them things that are high in sugar or carbs. Nuts are also a treat food and should be given sparingly.
as far as treats go, it’s better to give a tiny piece of fruit or carrot than even many of the commercially available treats. many of them are loaded with sugar. I personally really like the oxbow papaya tablets that binkybunny sells – they’re healthy and the bunnies go nusto for it.