1st question: generally no. But it all depends on which Operton model you're comparing to the X2 model. If you are comparing the same cores, then the power consumption would be equal.
2nd question: again, if you're comparing identical cores and clock speeds from Opterons and X2's, the temps are the same.
3rd question: you are confusing bus speeds; not your fault though. Opterons, Athlon 64's, FX's, and X2's in the Socket 939 or 940 format all operate on a 1Ghz clocked bus. However, some say and advertise it is 2Ghz because the bus is full duplex (it can send data back and forth at the same time). While the bus is truly only operating at 1Ghz, the effective theoretical data throughput would be 2Ghz. (it's just like DDR, PC3200 memory is really only running at 200mhz, but because DDR can transmit 2 bits per clock cycle, the theoretical data throughput is effectively 400mhz or DDR400.)
Make sense?
-mpjesse