Fursuit Etiquette

Really about the only rules I've heard are:
1) Have fun!
2) Know you're own limits.
3) Be safe.
4) See number 1.

Which pretty much means it's up to you how to act in when you're in costume. You should be aware of the written convention rules, but they're the same rules that apply to all attendees. For some other tips for general and specific fursuit performance, you may want to check this page from fursuit.org.

The reason you don't see anything definitive is because every costumer has different opinions of what the rules should be. Some fursuiters talk in costume, most don't. Some costumers prefer to have a spotter, some don't. Most of it is up to personal preference.

Actually there is one that I will add that is very important, especially in the USA these days:

#38: NEVER approach a child. You can crouch and wave, but let the kids come to you if they want to. Likewise, you can reach out for a high-five or a handshake, but these must be done at arms-length. Kids might offer a hug, which you can return, but just with the hands on the child's back. There must be nothing to even remotely evoke The Tigger Syndrome.

First things first.

Pittsburgh is HOT during the day. Even the Convention Center does not have the AC cranked up all the way (If Kage could look into that please? we were DYING while waiting for the Fursuit Parade to start and it felt like the Con Center was at least 10 degrees hotter than the westin!)So if you're going to fursuit for an extended amount of time do the following.

1) Get a sweatband, headband or something to keep the sweat out of your eyes
2) Know where the headless lounges are and use them... lots.
3) Make sure to stay hydrated
4) do NOT wear regular clothes under the fursuit
5) Plan a route ahead of time and if you get really tired and can't make it to your room, head up to a headless lounge, relax and then make it back the rest of the way.

And lastly

DO NOT SUIT IF YOU'RE NOT FEELING WELL.

Truuuust me on this.. I made a few of these mistakes and I learned firsthand not to do or to do these in suit.. heck I almost went into shock from dehydration.. because I wore a tshirt and jeans when I suited.. not good.

I second on the "Have Fun" rule.

1. Have fun (that's the point, right?)
2. Hydrate, hydrate, hydrate. Water is your friend.
3. Keep moving your head back and forth, and put a lot of motion in your walking. This not only makes your character appear more "alive," but also allows you to see your surroundings better. Your vision is severely limited, so you must act to compensate!
4. If you're uncertain of an area that you will be heading into, ask for someone to "spot" you, a person with eyes and ears that can help you avoid things like puddles, hazards which can damage your suit, or prevent you from bumping into people.
5. Do not overexert yourself. The moment you start feeling too hot or dizzy, get out of costume and get to a headless lounge.
6. Keep interactions with people short and sweet. Pose for cameras, perform acts, do what makes you happy and will entertain people.
7. Even though people can't see it, smile anyway! If you're smiling, you're happy, and you will perform better. People can "sense" positive emotions.
8. Avoid walking into areas that are cramped, dim, very bright, et cetera.
9. Avoid performing outside if weather is expected to be inclement. (I think that this is a given, though.)
10. Learning pantomime can be extremely beneficial. Study from other performers on their version of pantomime. After all, when you need to let people know that you need to use the bathroom, or are feeling sick, there needs to be some way to let people know what you need! (Crouch and point, hold your muzzle, et cetera.)

There are many other rules, but these are 10 that I can think of.

*edit* Uncle Kagé's mention of not approaching children should be paramount. There are many reasons, but I don't want to be on the receiving end of a parent's tremendous anger...

You may want to attend some of the "Fursuiting for beginner" type panels at the con. These are great places to learn from folks who have been fursuiting for a VERY long time, and can offer you lots of helpful tips.