Thanks @Redandblue11 
. It sounds like RedPup is going great guns and doing brilliantly!
With your DS coming down in the morning, I would redirect his energy. So when your DS is about to come down, have a toy at the top of the stairs for your DS to pick up on the way down.
Then say something like "Hey RedPup, DS is coming down now! Quick, get a toy!"
You have a toy ready too (I usually use a rope toy or a ball) and pass it to Pup, let him bounce up and greet your DS, and get your DS to get him to sit, and the throw/roll his toy or ball for him.
Each time Pup starts getting too boisterous, say "RedPup! Over here, grab a toy RedPup" and have a toy ready to give him, then "yes! That`s right! Take the toy to DS". Then get your DS to get him to sit before throwing/rolling the toy.
The idea is to get Pup to get a toy to take to your DS every time he wants to play rather than launching straight in with boisterous play, and getting him to sit each time gives him time to pause and calm a bit with a command he already knows well.
After a while, you can phase out both of you having a toy, and let RedPup find a toy to grab by himself, and as he gets into a routine of taking a toy to someone if he wants to play, he should pick up that play with your DS isn`t boisterous, its toy orientated.
As an aside, if he doesn`t already know "get a toy" its a very useful and quick one to teach - also keeps puppy teeth occupied at times when they might otherwise get bitey or boisterous!
Its usually fairly easy to teach, just "RedPup, grab a toy!" and pass him a toy, then "yes! Well done!" And again and again passing a toy, then pointing at a toy and letting him get it, and then letting him do it all by himself. I would use that to redirect boisterous behaviour too.
All that does depend on your DS being old enough and willing to stick with it, but I have found redirecting energy is usually a fairly fast working thing. If your DS isn`t able to assist, you can do just your part, and that will work too, although it may take a little bit longer.
For eating meals, our house is pretty open plan, but we have dog beds/a piece of vet bed and blankets in every room in a nook or corner.
I use "on your bed" for when we are doing something like eating or playing a board game. I find that a stay in place command works better for longer periods than just a "stay". Its just an extension of "stay" and once they`ve got that stay in place is usually quick to teach.
For teaching "calm down" I pick a time when Pup is getting a bit sleepy, and plodding about a bit.
Get him to come to you (or go to him) and get him to sit, then stroke him, rub his ears, whatever he likes slowly and soothingly, and say "calm down, thats right, yes, calm dooooooooown" and keep doing that until Pup relaxes. Keep doing it when Pup is getting sleepy, and then when hes awake but not tired.
Gradually start doing it when he is increasingly energetic, keep getting him to come to you, or go to him, get him to sit, stroke him and "caaaaaaaalm down, easy, that`s right, caaaaaaaalm down, yes, good boy" in a soothing tone.
After a little while you should be able to do it when he`s overexcited with the same effect. I do it with PolePup in the middle of zoomies if he gets a bit hyper, and it gets him to pause, take a few breaths and calm, so although he can be right back to playing, its taken it down quite a few levels, iyswim