It's great that you are taking in this poorly cared for rabbit.
Two years of age is not too old to be neutered. Do not give him a flea bath or any other kind of bath. Let the vet check him for fleas or other parasites. Advantage or Revolution is prescribed for fleas. You place a few drops on the back of the rabbit's neck (where they can't lick). If you have not made an appointment yet, go ahead and do so. If the rabbit does have any problems, it's best that they can be taken care of as soon as possible.
Since he has never had veggies or greens before, go slow with those, or you could get a tummy upset. Start with one veggie on the approved diet, http://www.rabbit.org/care/veggies.html,
then gradually add other veggies one at a time once a week or so. Some fruit is okay, but the yogurt treats are not. Rabbits shouldn't have dairy products. There are some healthy treats from Oxbow or other places if you did want to give him the occasional treat.
If the vet determines that he has sore feet, he may give you some treatment for that or tell you to get an imitation sheepskin rug or other padded blankets for him, such as a Snoozzy.
The vet should check his teeth, ears, eyes, take a fecal sample and possibly take a blood sample, as well as checking for parasites, feeling for lumps and bumps, any skin problems, make sure his weight is correct, etc.
Because you don't know his habits and since he isn't neutered which may cause him to spray, it's best to keep him in one area at first - making sure he has plenty of room, before letting him have the run of your house. An x-pen would be good for that, make sure it's tall enough so he can't jump out. You will need to bunny proof any rooms he goes in - protecting cords, putting up anything that you don't want him chewing on, etc.