Consider how much a horse weighs. Then consider how much one of your quail weighs. Divide the weight of a quail by the weight of a horse (make sure you use the same units of weight! Pound vs. pound, gram vs. gram, etc.) and then multiply that number by the volume of one dose of horse dewormer. That is the volume of horse dewormer you should give to a quail.
How often depends on how your quail are housed. If they're on the ground and have access to dirt or exposure to other animals, then you should deworm them as often as the horse dewormer suggests on the package. If they're in a pen off of the ground and are unlikely to be exposed to another animal, then you can just deworm them once and then again as needed. Many people who house large volumes of birds do it once a year. People with fewer birds often don't bother because the chances of infection are so remote.
For the equine paste, you would give them a "bee bee" sized amount, a one time dosage, squirted down the beak.
As for how often to do this, and as stated above, it all depends on the cleanliness of your facilities, are they on the ground, caged, etc...If you run a tight ship, and keep things very clean, then once a year will work. Twice a year if you are a bit lax or if you keep quail on the ground.
You can always get the quail poop tested at the vets office to see what type of worms you are dealing with. If you are only dealing with the most common of worms, the Round Worm, than a one day treatment of Wazine in the water will do once or twice a year.
I am sure this could be done, but I have no idea what the correct amount would be. They do make a liquid goat safeguard wormer you can use on poultry that you put in the feed. You can get it at TSC. This might be the way to go with so many quail.
Oh...you might want to try the safeguard pellets. I have seen them in the horse section of the feed store. I have never tried them, but it sounds like a good way to worm the quail. You might need to crush them up a bit as I do know the pieces are a bit large.