I have a brick fireplace and want to cover it with wood. I am unable to find a pre-made mantle to cover it and think I need to build it custom. I am just wondering what would be the best way to attach the wood to the brick?

Greetings--new woodworker here. I am about to make a small bathroom wall cabinet with 2 doors. Approx dimensions: 24"w x 30"h x 7"d (without doors). Face frame construction. Will top with small crown molding. Am ordering the doors (11" x 28" ea). My questions: (1) is a center stile needed? (2) I had planned to use 1-1/2" stiles and 2-1/2" rails. Is this acceptable? (3) I know everyone has a favorite joinery method, but does anyone have an opinion as to the quickest and easiest one for this project? I have access to a few tools in addition to the ones I own. (4) anything else/tips you want to share with this novice? Many thanks.....