I know most of this post is probably common sense but i'm going to say it anyways just because of how stressed you seem about the whole thing. I'm sorry for how much of this will be obvious.
The first time I ever got a chance to spend time with furries in real life, I remember that the experience was MOST interesting because I was interacting with a group of people that, for the first time in a very long time for me, spoke the same language I did. They knew all the same terms, they spent time on all the same websites... They had already seen all the funny videos and knew the memes... Hearing someone say, "Hey, what's you 'FA'" very casually in person was amazing... As were the hugs saying goodbye.
For the very same reason that it's awesome for furries to go spend time with other furries in person... Because we're with people who understand us and who, "Speak our language," so to speak, it's likely to be an uncomfortable if not increadibly awkward experience for anyone not in the fandom:
1. People who are speaking English right in front of them will appear to be speaking an entirely different language altogether and using terms they don't at ALL understand like, "Fursona," "scritch" or, "Handler."
2. People will all have their own common experiences and a sense of similar background that they do not have and can't relate to.
3. People will behave in ways instinctively and naturally that you do not in normal society. Someone doesn't have to pouncehug him for it to still be odd to see someone walking up and scritching a friend or everyone exchanging hugs when introducing others.
While i'm sure this certainly isn't the case in all furry situations, these have been my experiences meeting with furries in person and there's bound to be all sides of the spectrum at a con.
That being said? You are likely to be the only thing he has even close to an interpreter... And he'll be trying to gauge how normal things are based on your reactions. Looking extremely awkward because you're worried what he will think when a friend randomly runs up and hugs you is likely to put him on edge while... Counter-intuitively, enthusiastically hugging the person back like it's the most normal thing ever is likely to put him at ease. He's going to need a break from time to time to process things. ...And most importantly, he must never feel abandoned or like he's not a priority in the midst of all the chaos over the weekend.
Don't bring up sexual deviancy yourself. There's not ever a good reason to. If he tries to bring it up, just downplay it and say, "Every fandom has it's dark corners."
