Well, the vet seems to agree that he's Bengal or at least part Bengal. Luckily he hasn't taken any harm from being out in the wilderness for at least a month and is all around healthy. (Except for worms and fleas, which he got treated for, and the tiniest little scratch on his nose, possibly from getting too close to another cat.) I guess I'll be hanging around these forums a little bit longer!
One question: Is there a way to discourage him from spraying after he started? The vet thinks he's about 10 months old and we're planning on neutering him in three weeks when he gets his booster shots, but since he already started spraying it might be a bit too late to prevent that behavior.