A mill having a fixed Z turret and moving X Y slides, and a router having a fixed table and moving gantry?

So if wanted to mill, say chocolate moulds, , as an example thats come up before,fairly deep/ high level of finish, in steel, would really need to be on heavy iron fixed turret mill to get there?

If wanted to cut square holes in 2.5mm mild steel , a moving gantry router would be feasible but probably not optimal?

Yes, strikes me that cutting holes in plate is more a plasma cutter or for quite a few dollars more laser optimal operation, just looking at ideas at moment.

Appreciate people taking the time to answer what are very basic questions.

Cheers
Adam