Per the Ortho Weed-B-Gon MAX Plus Crabgrass Ready-To-Spray label instructions, you will use 2.5 oz of the product per 1 gallon of water and this will cover 400 sq feet, so you would use a total of 6.4 oz of product and 2.5 gallons of water to cover 1,000 sq ft.
Per the product label, areas that have been treated with Ortho Weed-B-Gon Plus Crabgrass Control Ready-To-Spray can be reseed 4 weeks after the application. On new lawns, you will need to wait until the new turfgrass is establised and atleast 2 inches in height, after the 2nd mowing or 30 days.