What are the most important tips you can think of from day one of bringing home a puppy into a house with other dogs?

I'm thinking the best idea would be to build a run to keep her separated from the other 2 dogs so she bond properly to be and doesn't get bullied by them.

What are your experiences and advice on raising a schutzhund puppy?

Keep separated till 10 months old or so, slowly introduce them then. From 8 weeks to 10 months I let them interact for short periods of time once in a blue moon so they can become familiar with each other. Usually I wait till the older dog totally ignores the puppy when in the crate and has accepted that the puppy lives there now.

Kennel run is nice, but do you plan on letting him pee and poop in the run as an adult? If no, then I would crate train the pup first before introducing the kennel, and only limited amounts of time when you are sure they arent going to poop. Otherwise it will be a hard habbit to break if you don't want it.

If you want them to pee and poop in the kennel, then start the habbit young, because a well house broken dog might refuse to do so as an adult

I brought a new pup home in the house with my other adult dog recently. Albeit, the pup was 13 weeks, not 7 weeks. I let them interact and eventually play together in short intervals always SUPERVISED and always kept both dog and pup on a dragline. Since the puppy was 13 weeks and still with her sister in the kennel, she was pretty damn tough. The older dog (2 years old) is a woosy-pussy anyway and although she can get nasty she'll submit quickly to my voice command, or my wife's. They were never together alone, and never will be.
I wouldn't put a 7-week-old puppy with older dogs for more than a little sniff about a week later.Puppies are pretty fragile, and one bad experience can ruin your Schutzhund prospects.
Now that my pup is 6 mos. old, they can't play together anymore cuz it gets too rough. But they hang out together in our living room...again, closely supervised and both with 6-foot dragging lines.
We tradesy-off time in the crate and training/play time. I take the pup to work and the older dog chills in the crate all day. (I work for myself and have a crate in my office so it's ok)

I recommend all of Ed's videos on Schutzhund training. There's one on raising a working puppy and others on puppies 8 weeks to 8 months, I believe.

I think it would be best to let it pee and poop in the run. What size would you advise on? Would it be best to have a kennel in the run?

I've got 8weeks to 8months but wondered how much it differs to raising a working puppy?