The first thing you need to figure out is what your goals are for your flock, and why you want a roosters. If you want to hatch chicks out from your flock, a rooster would be a good addition. If you want one for "protection" of your flock, you may want to reconsider. Yes, roosters will raise an alarm if a hawk flies over, and sometimes for ground predators. They may even take on a raptor or ground predator. Some even win. The rest are just a speed bump - the rooster dies, then the rest of the flock is next. A dominant hen will often take on the role of a rooster as far and watching for predators, etc.
Blood in your eggs can happen with our without a rooster. Sometimes it's a glitch in the assembly line that causes it. Fertile eggs don't develop blood vessels until after a few days of incubation. Collect your eggs daily, and that won't be a problem.