DB - I see what you are saying, on the N3 we set a DA bug on the altimeter tape to the minima we are flying to and use the DH bug on the rad alt tape for ground proximity. The audio warning is only from the rad alt (DH) bug.
We make the decision approaching DA and go around without descending below that. This is a slight difference from what the military do where the decision is made at DA (DH if on QFE) and the go around can go below that figure.
Our standard settings for rad alt are 200' for non-precision and 100' for precision approach.
As I understand it, the figures in brackets are for those that fly the approach on QFE rather than QNH - we do both depending on whether it is a civil or military airfield.
tistisnot - completely agree except that a height ie DH must be based on the airfield datum - if it is referenced to msl it is an altitude and becomes a DA.
QNH for DA/MDA, QFE for DH/MDH.