We cannot tell you how to play your character, nor can we tell you how to "talk IC". You are right in saying that the CAI is more realistic, and that is what we are truly going for. We want, as stated in the FAQ, a room filled with imagination, and creations... we want the room to "feel" as realistic as possible, as we believe it makes for better roleplaying.
On a personal level, as far as my personal opinion goes. I believe using "can't, don't" etc, shouldn't be involved in roleplaying in a setting such as the CAI. Individuals in the medival/renaissance time frame used no such words, however, on the other side, using the shakespearean language such as 'ye', 'thy', etc.. can truly get annoying if not done properly... meaning if it is overused. :)
As for the rude behavior you encountered, I understand that you may not know if it was a joke, or directed straight at you... regardless it will not be tolerated in the Inn. As I said before, the Court has plenty of that for the entire EW (trust me, spent over 3 years there*L*) Sooo...
Hope to meet up with you soon so we can rp our characters :)