Getting everything cut to the exact same size is a possible issue. You might be able to use your table saw to cut everything exactly parallel and flat. Make a sled with clamps on it. The sled has a straight edge and/or miter bars so it goes straight into the blade. Use this sled with oversized wood to cut a perfectly straight edge. Use that edge against the fence, and cut to exact width. Cut your posts the same way from a long piece with pre-cut slots. Use the table saw to cut the tenons on the ends of the side pieces.
If you don't have a Wixey Digital angle gauge (new ones use AAA batteries) to make certain the blade is set precisely to 90 degrees.
For boxes, if you're going to make many, pop for the blade that has quarter and 3/8ths sizes depending on how you install the blade.
Lots of ways to skin this feline.
The more I do, the less I accomplish.