I assume the temperatures and fan speeds disappeared due to a mismatch of OpenCL and ADL devices (according to the following text at cgminer's start):
I have the exact same problem. I'll let you know when I have found a solution. I have no clue about your other problems. My cards are always running at the same speed, with or without monitor. Even remote (ssh) has the same values. I did have some problems when I was running on Windows, but most of the time I could fix that by reinstalling the drivers.