They have the Korky 528MP valve that Terry recommends at every Lowe's and most Ace Hardware's. They don't have this model at HD, and the Korky valve that they do have at HD doesn't refill the bowl enough.
Your "funny" comment about water and flushing is really, really wrong in this case. The waste Terry is talking about is the refill water that just runs out of the bowl and serves no purpose whatsoever. Here's why: every toilet bowl has a natural water level. Any water (or urine or whatever) that you deposit in the bowl displaces other water and causes the balance to run down the drain. When the flush cycle has completed and the toilet bowl is full and has settled to its natural level, any liquid you dribble in will cause a corresponding amount to dribble right out. You can see on the diagram below where the water in the bowl levels out at the "weir" of the trapway. Anything that you add to the bowl will cause that water to flow over the weir, down the trapway, and out the bottom of the toilet. (When you flush, you put a lot of water in there are once, so the entire trapway fills like a straw and a siphon is created that sucks the entirety of what's in the bowl out, then the siphon breaks with a gurgle when the bowl is empty, then it starts refilling.)
SO...water saving toilets have the refill percentage (the portion of the water coming into the tank that is diverted through the rubber refill hose and down the overflow riser to refill the bowl following the evacuation portion of the flush) carefully-calibrated to have the bowl fill just to its natural level exactly at the time the tank fills and shuts off. That way, no water just runs down the drain for no reason while the tank continues to fill. The Korky 528MP valve lets you set it so that it duplicates the manufacturer's calibration of that refill percentage. The 400A doesn't. So, a perhaps-not-insignificant amount of water is going to continue to run into the bowl after it refills to its natural level, then dribble over the weir of the trapway, and be wasted down the drain, accomplishing nothing.
By the way, the spec sheet, parts list, instructions, etc., for your toilet are all available on the Toto web site.
www.totousa.com Look up either CST744SD (elongated bowl) or CST743SD (round bowl) for the complete toilet. They both use the same tank, which, as Terry said, is the ST743SD insulated tank.