I have used metal/stone cutting and metal grinding and I found that metal cutting gives the best grind,just as sharp as stone cutting,but more fine somehow.
It will be visibly smoother than new,so you should be able to see it without actually touching the rim.And to the second question,it depends on many factors,but average lifespan of a good grind is 1-2months(based on time spended on the bike)
It´s normal that it doesn´t feel the same on the fingers(pads smoothen the sharp metal shavings or whatever you call them of the rim),but it doesn´t affect the performance at all.