OCC is "One City Challenge" (I hope). It's a special variation on the game where you build only a single city.ICS is "Infinite City Strategy" (also called "Infinite City Sleaze" by those who dislike it. The idea is to overwhelm your opponents with minor production from many small cities instead of major production from a dozen good ones.
To play multiplayer (mp) games, you need the Multiplayer Gold Edition and you need to download a patch. The patch is available from microprose.com or from a location here at Apolyton. It solves an incompatability problem.
If you have a city in revolt, I don't think you can get out of anarchy. Examine your cities before Revolution to make sure they will survive the transition. The Attitude Advisor will help. The change to Monarchy is shorter than to the others.
Cities change their trading needs from time to time (I don't know specifically what triggers it, though the city size and techs must play a part). I annoys me, too. Consider selecting a target city that has a few barely smaller cities nearby, and check the demands of the target city while you still have optional routes ahead of you.
Sometimes, it is worth putting a caravan to sleep for a few turns while you hope for a different city to want your goods. Leave it on an out-of-way swamp or mountain.