***Putting this in the care corner because I'm a novice when it comes to rabbits, and just in case anyone has advice... but I really do think I need moral support and an introductory thread for little Jeff just as much.***
I've had a long day... not to clog up the bunny forum with off-topic stuff, but some of you might recognize me from the ratties section of GM and Toph had to have an abscess on his face lanced today... I was doing a TON of frantic apartment-hunting and in the middle of all of it my best friend (bless her) called and asked if I would take this rabbit she just rescued from a meth addict who had Jeffrey (the rabbit) in a cage that was never cleaned. One area he had peed on so many times the metal rusted through and was jagged, the wire was not coated it was just exposed rusty wire, the entire bottom of the cage had a layer of filth that could not be cleaned, his water bottle was moldy and he had mats on his head. Rachel (my friend) immediately got him out of that cage and got him a cleaner one, although it's kind of more of a temporary thing.
I'm giving myself a crash-course in Bunny 101 right now, I know some basics but nothing in depth about training, playtime, diet, etc. I am perusing the forums here and Binkybunny as well as google so I don't expect anyone to spoon feed me info right now, but if you have any helpful tricks/tips it's still appreciated.

Jeffrey is slightly under one year old, maybe 6-8lbs, and apparently sexually frustrated because he's humping everything haha. But he's a big sweetheart, he is socialized and not scared of people at all so he likes to cuddle and give kisses. I haven't seen him eat or drink any water yet which kind of concerns me but he does have access to fresh hay and some pellets right now.
As I'm looking up some of this stuff about enclosures and so forth I'm realizing this cage he's in now is really not going to be suitable, however, I don't know that I have the funds to spend on a big enough enclosure right now, and I rent a room from someone who has a cat, and then I have my two little rat boys. Jeff will not be able to have free range of the house (tbh I didnt know that was a thing but that's awesome) although I will be able to shower him with attention, let him out of the cage a lot, give him fresh veggies, etc. But I don't know if I will be able to keep him permanently. Now is a weird time in my life and I'm not sure if a bunny is the perfect pet for me considering I have so little experience with them and he kind of happened so spontaneously... but Rachel didnt even have him until around dinnertime today and there was nowhere else to keep him, and we really didnt want him around the lady bunny for obvious reasons, neither are "fixed." I can take him right now or I wouldn't have, but the extra expense as a regular thing, idk if I can do with Topher and Mishka racking up vet bills as fast as they have been.
But yeah... I will be looking into probably rehoming him or taking him to a respectable rescue if I can find one around here, in the meantime I will just shower him with love and healthy food cause he obviously did not get any for a while. But I don't want to just shove him off to a random shelter where he will just continue to get locked in a tiny cage and ignored (even if he's not neglected, I want to know he's going to an animal lover this time). In case anyone is wondering, I am in the (north) Fox Valley area of Wisconsin. I know of a ferret rescue a few miles from where I live but not a bunny one unfortunately hah.
Here's his handsome face:

Cage size - rachel had to get an emergency one from fleet farm so its tiny, sadly:
