Yes, he is definitely on the small side for his breed. I've read that the minimum show weight for bucks is 13 pounds, so he is on the low end of the scale.
He is the fawn color and it seems like all the fawns I have come across have been on the small side too. It's weird, but the only large ones I have seen in my area are sandy or gray. Just out of curiosity, what color are your bunnies?
No, he is not yet neutered. But he has an appointment in 2 weeks. I've been in contact with a local rabbit rescue group and met a few bunnies that I like and hopefully he will too. They still need to be fixed as well, and one of them is still recovering from being malnourished, then we will try the introductions. But it is probably a month or so away.
Thanks for the cage recommendations. I might end up affixing an exercise pen to the cage to give more floor time. I saw a few cages like that on this site and I liked the idea.
~Eris~