Can you close the blinds/draperies at the front window? I know that can be inconvenient, but sometimes, management is the first and easiest step.
As for barking, I've found that "Quiet" is probably one of the most difficult commands to teach a young dog.
I use redirection. I ask for a behavior that is incompatible with barking. "Come" is my favorite (as long as the dog has a reasonably good recall). It especially works well in a house full of dogs because the dog that arrives first gets the treat first (and the biggest treat).
When we're out in the front yard, if I glimpse someone way down the street, I tell my dogs "come," trying to get them redirected before they notice the stimulus. (Sometimes, I notice it first, sometimes, I don't. But as soon as I hear a tiny peep, I call them to me). I can then hold their attention by giving them itty bitty pieces of treats, or by pulling out a favorite toy (a frisbee or tug toy). The point is that I make myself more interesting than what's passing by.
Once it's gone, then we play. Since you're in the house, you should be able to redirect them more quickly. I used to have a dog that liked to bark in the house, but I was able to train her to stop that using this method. I tossed the toy down the hallway AWAY from the front of the house where she could easily see/hear the stimulus. With a dog that you plan on doing SchH with, playing tug seems like a good fit.
The only fallback to this approach is that we want to avoid creating dogs that bark and run to you for a reward after barking (in other words, they feel like they're being rewarded for barking). That's why you have to be sure to use the word "come" (or whatever your recall word is), and not repeat it over and over if he ignores you, but DO get your dog if he doesn't respond the first time. A lightweight drag leash can be very helpful here. Pick up a 6' (or so) lightweight leash at a pet store and let him wear it all the time around the house. It will be a nuisance, but my pups wear them for quite a while, and they never hurt themselves or anyone else.
Dog barks. You: "Fido come." Fido continues to bark. You pick up the leash and reel him in, telling him as he arrives, "good come. "
Often, once dogs start barking, they kind of get into a zone where they don't listen to us, so we have to break into that zone. A drag leash helps with that. Once they realize, "hey, I have to listen to her all the time but there's a benefit for me to do so," then the zone will have less of a hold on him. Soon enough, you'll be able to get rid of the drag leash. At that point, you can move toward using a clicker, or simply, he'll be dashing toward you for his treat (or his toy) and you won't even have time to click.
Teaching Quiet is a whole other ball game. For the most part, it needs to be done when your pup is calm and peaceful. When your dogs are lying around, doing nothing, but hanging out, being good and quiet, walk up to them, and exclaim triumphantly "good quiet" and treat them. Do that over and over and over and over. Eventually, they'll realize that Quiet means quiet. It doesn't mean "barking my fool head off" (which is usually what dogs are doing when their owners are trying to train them to be quiet). Quiet takes lots of time to train it correctly. It's definitely worth doing. But it takes time.
For right now, I think redirection is your best bet.