Coccidia is a protozoa, not a worm. Sulfa drugs are typically used to treat infections, but I believe Panacur can be used as well.
I’m not sure why you’re so worried about it though. Even if it is common in your area, food needs to be contaminated with oocytes and then consumed in order for a rabbit to become infected. Pellets, hay, and washed veggies are a pretty low risk diet. The risk is much higher if the bunny is allowed outside where they can eat grass that may have been contaminated by wild animals. I wouldn’t worry unless your bunny is displaying symptoms of an active infection.
As for flea treatments, again, not much to worry about unless your bun is outside for whatever reason. This is particularly true if you don’t have pets. Revolution and Advantage are safe to use to treat fleas. Keep in mind that rabbits metabolize them much faster than a dog or cat. There have been reports of Advantage only lasting a week or two.