When an alternate minimum applies, does it change MDA or DA? In US, the weather minimums for an alternate airport are typically 600-2 for precision approaches and 800-2 for non-precision approaches at ETA, unless otherwise specified at US Terminal Procedure Publication.

When it comes when we actually fly the approach, 


a) Is the DA raised to 600 for precision approaches?
b) Is the MDA raised to 800 for non-precision approaches? 
c) Is the visibility requirement raised to 2SM for approaches at an airport? 


Do alternate minimums work similar to inoperative components, use of alternate altimeter settings, NOTAM to change the actual minimums we use to fly, or a purely preflight planning number for selecting alternate airport?
From the FAA Instrument Procedures Handbook, section 6-4: "The 600-2 and 800-2 rules, or any exceptions, only apply to flight planning purposes, while published landing minimums apply to the actual approach at the alternate."