My first Furcon was Anthrocon '14. Began where i felt very awkward but i did eventually find some of the furs from my neck of the woods who were attending as well and from there it became quite the experience. I did some suiting, walked in the fursuit parade, bought and commissioned art and whatnot, then my friends snuck me into the masquerade and afterwards I got to meet a couple of more well known furs so to speak so it was a pretty awesome experience, not to mention it did solidify my friendship with that group. Going again this year so we'll see what happens.
As for fursuiter courtesy, it's considered common courtesy to ask to hug them or take a photo, like for example they'll put them arms out for hugs and whatnot. As for talking in suit, Me and my buddies chat in suit all the time and we never really caught flak for it, not to mention my fursona has his own voice.
As for not having a suit, most people just have a tail or ears. Some cases they just wear plain ol' everyday clothes, heck there's even the occasional cosplayer.
As for the experience, generally best to just experience it for yourself and see what you take from it in all honesty.