If you have planed all your true faces and edges for the table legs, you can now set your marking gauge to the thickness of your legs (they are as wide as they are thick) and do your layout with one setting. Take a second to try a few spots on each board before you mark everything in earnest, find the thinnest spot on the thinnest board and subtract a hair from that…this should be your setting, it should also be fairly close to your story stick, if not, no worries, just get it close.
Mark around the entire piece and take a minute to look at how much material you have to take off. If you have the room remove any cup twist or bow before you try to make the surface parallel to it’s opposing side (this simplifies the adjustment process). Make adjustments be taking selective shavings on the high parts of the board and check you work often. I am taking things pretty slow in the video because it’s important to try to get this step right. My master used to say “accuracy first, speed later”, he was right, get to the point that you can do something consistently then learn how to do it fast.
With any luck you will have one whisker left on both corners, with one final pass of a plane. If not you live in reality land and things are not always perfect, this is why you plan for imperfection. The face sides are on the inside of the board to accept the joinery, any inconsistency gets thrown to the outside where no one (not even you) should notice it. The whiskers come off later when you smooth your work and break your edges so leave them alone for now.
As far as the true face and edge for the rails, I would pick the pretty side to be true and put it on the outside, and the top to be true since it has to mate with the underside of the table top (a slight hollow is ok but avoid a hump on these edges like the plague), this way small inconsistencies are thrown to the bottom edge and the inside of the table where they will be almost impossible to detect.
Once all your stock is true, your are ready to for joinery. Don’t rush this part though, it’s the building block for everything else. Take your time and enjoy littering your shop with shavings.
-- Make furniture that lasts as long as the tree - Ryan