1) Yes
2) Hot enough that you can't keep your finger on it for very long on the back of the board over the VPU
3) I would not replace it unless the fan isn't working. There is a support shim around the core that raises the HS above the core and the space must be compensated for. Search the web for radeon VPU/GPU shim and you will find info about this. My advice is to leave it alone if it is working. A common replacement HSF is the Iceberq 4.