Patching and Plastering - Sheetrock over brick

Hi, I am remodeling a house that had a porch enclosed to create a sunroom. In order to make it feel more finished, I'd like to cover the brick columns with sheetrock. Do I need to fur this out or can I just screw sheetrock directly to it?

Also, in my existing bathrooms, I've removed the tile/mesh/mortar wainscots from the walls and would like to just have them sheetrocked. What is the preferred method? I have a 3/4" thick plaster over gypsum board set up currently, so should I do two layers of 3/8" or should I fur out and do 1/2"? I've seen some people say just mount 1/2" then apply skim coats to flush things out, but that sounds intense.

It will probably be a real pain to attach the drywall directly to the brick, I'd advise furring it our, could use 1"x material for this if you want to conserve space.

My suggestion for the bathroom issue would be to fur that out with 1/4" material of some type, all you would need is some strips of old paneling cut it in strips & attach to the studs and then put your 1/2" rock over that and you'd have your problem licked.