Admittedly, I am most experienced with SciFi, Anime, and Fantasy conventions, but I imagine many aspects still transfer to Furry Cons.
Know the "weapon" rules. A more accurate description would be "prop" rules, as that plushie ham you carry is considered as much a "weapon" as a plastic Nerf sword/phaser, or in the rare occasions the con allows it, live steel. Cons such as KumoriCon and SakuraCon only allow plastic, foam, and wood weapons. Live steel (or any metal for that matter) is not allowed. All weapons must be "visibly" peacebonded, which in this case is usually bright flag tape around the weapon, signifying you read the rules about not performing sword fights in the halls. Cons such as NorWesCon and RustyCon allow you to carry live steel weapons, but they must be "fully" peacebonded (basically zip-tied so they can not be drawn or trigger pulled), must always be sheathed, and never drawn in public space. Ignorance is not an excuse, and every Con I know of with these slightly more lenient weapon rules goes by the, "If it's drawn, it's gone" rule. I have also attended RingCon and Tolkon (as well as a handful of Ren fairs), both of which allowed members to carry live steel weapons, such as axes, swords, halberds, and pikes unsheathed. I honestly feel a little uneasy with cons allowing brandished live steel.
While most will allow you to take pictures or film of their costumes, ALWAYS ask first... ESPECIALLY if it is a minor. I cannot stress the minor enough, as I have been on security, and know of several instances of someone being escorted from the con by police officers. I myself am an avid cosplayer, and put hundreds of dollars into my costumes. Perhaps it is just vanity, but everyone likes to be admired by the hard work they put into making, or in the least gathering or commissioning their costume. Even if I am rushing to a pannel, or even just stopping for food or shopping in the dealers room, I am always more than happy to stop, and pose for a picture, if asked.
To expand on fursuiters not liking to be "Glomped" (the action of one person lovingly [and dramatically] attacking another with a hug), for the most part is untrue. Usually, we are happy to give and get hugs. The largest problem is that the suits are so large and cumbersome, and our view through heads and masks is limited, usually we don't even see you coming. My advice is to be sure you are in front of the fursuiter, start from a distance away, and move slowly. If you give us an idea of what you are doing, like opening your arms wide for a hug, we can anticipate, and not be knocked over. Also, look for a suiters handler. This is the person who is basically leading the fursuiter around. They are able to pass information to the suiter, and acts as a second set of unencumbered eyes. Speaking with them allows you to get a posed picture, or a hug.
Like I stated above, I have put hundreds, and in a few cases thousands, of dollars into my costumes, as well as countless hours creating them. It is always painful to see any costume damaged, especially my own. Having lost a $500 cat mask to someone not paying attention, I cannot stress enough to be careful.
You are more than welcome to be that squeeing fanboy/fangirl, and for the most part we love it.