I have not read the other posts, sorry, it's late and I don't wanna!

But, what a dog!!! Weimariners are my favorite, we've had two and although they are nut jobs I love them. We also have, used to breed and of course love labs.
Anyway, food: we've found the best thing to get is from a feed mill. When we lived in Missouri, we got something called Black Gold. When we moved back to PA, it was JOY and now something else (it was just changed by the suppliers.) Check for a high fat and high protein food. They'll eat less and it's great for the larger dogs. We tried something else for a year and when people saw our Christmas cards the next year (one of our girls is always on our cards) they wanted to know who the dog was, she'd lost a lot of weight. Didn't notice seeing her daily, but they did seeing it once a year. A 50 lb bag lasts about a month with 2 labs for us and it's about $25 a bag, not bad.
I might have to check into feed stores. It is about a 45 minute drive to Petsmart/ pet specialty store, so I would prefer to find a good dog food closer to home if I can. Its one thing to run out of milk and be able to go to the grocery and pick more up, but a totally different thing to "realize" your out of dog food on a Sunday evening. I am not against Pet Store Food, I am just trying to get information and make a resonable decision. I also want to avoid getting a "specialty" food that is only available in limited, not easily accessible, locations.
Fleas, bath the dog in Dawn dish soap, kills them right away. If you can, keep the dog pretty much in one area and use borax on the surrounding areas. IE we had a bad flea problem one time, kept the dogs in a LARGE dog kennel for several days, they got out a few times a day to run in the yard. We put borax all over the carpet around the kennel. This dries up the fleas and eggs. Works great if you are in the position to do it. Being pretty new to the family and young, may not work for you though. Treat the dog with advantix or advantage (our favorite) something from the vet to be sure it's good. I've never found any of the stuff ya get at Walmart to work.
I bathed him in watered-down apple-scented Ultra Dawn last night. How will I know if its working/ has worked?
You are lucky he's kennel trained, it's a great thing. PLEASE PLEASE (my sister didn't listen and regrets it) don't "unkennel" train him. A Weimaraner is smart, sweet and, ummm, sneaky. Once they are allowed to not be in a kennel, they are likely to not EVER be willing to go in again. Sis has a part lab part Weim, a friend had full Weim. I told both of them, USE A KENNEL, both said "oh, but they're so good without it, it seems so mean, we'll let it go". Within a year they were both crying to me that the dog was destroying things in the house and ended up destroying any kennel they put it in. Take advantage of this benefit!
I think he is going to be quite a bit bigger than either of his parents, and am afraid he will out grow his current kennel. It is difficult for them to "switch." What is the best way to change out his kennel? I have no intention of not using it. He likes it, and I've never heard of any expert saying it is mean to kennel a dog, in fact, they say the opposite. Some dog owners think it is mean but that is because they look at it from a human perspective, not a canine perspective.
We were told by a trainer that a great toy for a Weim to keep their minds busy, is a Kong filled with peanutbutter and frozen. They'll lick and lick at it. We used pigs feet... not sure any more that's what they're called, also got them at the feed mills, hard hoof things... we used these when the puppies would really start chewing. It was great, they loved them and they stuck to them, never had issues with chewing on stuff they weren't allowed to.
I know this is long, and you probably heard it all already, but I couldn't resist, I do love my Weims and labs! I hope you enjoy your new family member!