Definitely have him neutered. Male rabbits are territorial and they will spray urine which is horrible. When we first got Wolfie he wasn't neutered and he was like one of those sprayers that you see spreading pig muck on fields. It went everywhere and had terrific range. I got caught a few times I can tell you!!
Female rabbits get moody when they get sexually mature and territorial too - bit like long-term PMS. Also I believe that spaying them helps prevent them getting ovarian cancer which is reputed to kill a lot of female unspayed rabbits when they get older. It doesn't cost much and your get the benefit of being able to have two bunnies who will love each other as long as the bonding goes well. My two sit huddled together, grooming, snuggling and they are never too far apart. As I am out at work most of the day, it is nice for them to have their own company. I would never keep a single rabbit unless I had to.