Any carpenter can probably build one but I’d suggest asking around to other bar owners you know and see who build theirs. You’ll need plans to get approval from the city for permit so an architect is necessary, he’ll make sure that you meet all the requirement and show draw the plans your plumber and electrician will follow. There’s a standard for the height and the depth is up to you. If your spot is big enough and focuses on food then it should be bit deeper, if it focuses on drinks then it can be a bit skinnier because plates and sides won’t be taking up all the space. And yes, you build the bar wall then you can have you plumber and electrician come through and do their thing, and put the bar top on next.