Verant's policy is that they will help players who have problems with game driven issues, but will not assist players who have issues with connection or who just end up in the wrong place at a bad time. Most of the GMs I have met are pretty understanding and helpful, however there have been some pretty lousy GMs and it only takes one to ruin your playing experience. Verant has been trying to improve their online customer service face and they've done pretty well. Verant publishes a list of current bugs and prioritizes them on their website. On the whole they are pretty slow to fix bugs unless there is a serious and immediate effect on gameplay or balance.
Patches go in about every second week, which force the clientside to update.
Most patches are pretty mild, but a when a serious patch is put online there are a lot of unannounced changes, some creating new bugs. Every change to the world of Norrath is tested on a special test server, but it doesn't always find bugs that show up on production servers. Patches also cause many ultra rare monsters to respawn and once the servers open up again there is a mad rush for players to get their characters to claim those nasty camps. Playing Everquest can be very demanding. If your computer barely makes the systems requirements, or if a little lag hits you, it can be difficult to control your character and respond in time during big fights.