Ivermectin is not considered effective against tapeworms. It may have killed some of them, but you should use something else. Praziquantel kills tapeworms specifically, but does not kill roundworms or other worms, so it is often combined with medications like Ivermectin that don't kill tapeworms. Albendazole (Valbazen) and Fenbendazole both treat roundworms and tapeworms and are generally considered very effective. However, Fenbendazole should not be used when chickens are growing new feathers as it causes deformity in the new feathers. I like Valbazen, but you should not use the same dewormer every time or the parasites become resistant. So pick a few that treat what you have and rotate them. If you already treated for roundworms, you can treat them with just Praziquantel for the tapeworms. Another product that treats roundworm, tapeworm, cecal worm, hook worm, and threadworm is Wormer Deluxe. It comes as a powder that you mix in their water for 2 days and then repeat in 21 days. It is available from pigeon supplies. I haven't used it yet, but I have seen it highly recommended several times.
Regarding depluming mites, I have found several things that are effective, but no matter what you use, you should repeat treatments several times initially, and then periodically. I accidentally found that Revolution (Selamectin) treats depluming mites when my avian vet prescribed it because a few of my hens had stick tight fleas, and after that, one of my poorly looking hens grew new feathers. The dose is 0.5 ml per standard sized chicken and 0.25 ml for smaller pullets and cockerels. Subsequently, I have used lime sulfur dip and sulfur dust. I made up the dip according to package directions and dipped each chicken for several minutes, making sure to wet all feathers. I did it on a warm day and did not dry them. Watch their eyes because it stings. My remaining chickens with damaged feathers started re-growing feathers after this treatment. I used Vet Basics brand but there are many and I believe they are a standard concentration.
https://www.chewy.com/vet-basics-lime-sulfur-dip/dp/163591. Since then I use sulfur dust for maintenance on them, on their roosts, poop boards, nest boxes, bedding, and dust bath spots. I use BONIDE Sulfur Plant Fungicide Dust because the powder flows better than regular sulfur powder. It is labeled for this use. Here is what the product info says.
"SAFE FOR ANIMALS - Helps control fleas and ticks on dogs, horses, cattle, swine, sheep, and goats. Can also be used to control depluming mites on chickens, turkeys, ducks, geese, pigeons, and other game birds."
https://bonide.com/product/sulfur-plant-fungicide-dust/