Just finished - 1 week ago - my garage and now need to buy the paint.  Walls of garage are plastered.  Any advice on good quality primer and paint for the walls and the floor.   Also want to treat the concrete surround.  I'm told TOA epoxy primer should be top of my list but seem to be many to choose from and I am in no way an expert.  Advice would be welcomed.

just to add to your post...I would like to replace tiled bathroom walls with plain concrete...the walls are painted while underneath the concrete, and are fairly smooth, except for where the pipes are.  Would like just a grey cement look....but could use primer paint, if better.  Seems like stripping the walls completely would require more resources.  Perhaps some type of thin coat, or even something like a textured garage floor paint.  Got to be waterproof.  Thanks for your suggestions!