We had same problem here last year, a fox took two of our chickens from the coop. After that, we reinforced the coop with iron bars to keep them safe. Also make sure the coop is spacious for the chickens to move freely. As for roosters, it's better to keep just one to avoid fights, as multiple roosters can become territorial and hurt each other. And I don't think one rooster will make too much noise. Plus, one rooster is enough to fertilize eggs if you're breeding.