I just reread your post! Sorry, my eyes were closed the first time, after a long hard day! Now I realise you're taking bunny on. Good for you!!!
It sounds like he could use some love and attention. Definitely get him checked over by a vet (where abouts are you, maybe someone on here can recommend a bunny savvy one?) and have them double check he is a boy too.
If you are interested I recommend Readigrass and oat, wheat and barley hay for fussy rabbits. What are his poos like? Probably squishy with his tooth issues? If so be sure to check his bottom every day and clean him if necessary. Flies can lay their eggs on a soiled bunny and that is bad news!
Make sure the vet gives you metacam. It's a painkiller for bunnies, and luckily they find it delicious so there shouldn't be any problems getting him to take it!
Has bunny been living outside or is he a house rabbit? If he's been indoors he'll need to stay that way until late spring, as he won't have his winter coat. Being social animals it's never fair to keep a single bun alone outside anyway. If you'd like him out there long term consider adopting him a wife, when his health issues are under control, and after he's been neutered of course.