More details required! I feel I may be able to answer your DA and MAPt questions, but tell me what "paretheses" you mean. It may be helpful if you say what chart(s) you are looking at. Are we talking Cat II ILS or CAT I? Or are you looking at a Military or joint use aerodrome? Also, you obviously can't follow a Missed App. Procedure if you've rejected the t/o. So please clarify.
For now, I'll limit my reply to the one clear bit, which is that the MAPt has no use in a Precision Approach. It's on the plate in case the GP fails and it becomes a non-precision Approach(LLZ only).