Hello there and welcome to BYC!
Congrats on the new flock but not all those yucky mites!!
Definitely follow the links that NorthFLChick has left for you. You can use Ivermectin Pour On to treat the mites on the birds, but many mites get off the birds during the day only to feed at night. So you will need to treat all surfaces and cracks in the wood with a good permethrin spray or poultry spray. Clean out all bedding from nest boxes and spray or dust in there really well. Treat the roost bar especially and under neath the bar well too. Mites like to hide under the bar in cracks and come out at night to feed on the birds.
Every 5 days clean out all bedding and repeat the cleaning and spraying procedure.
The dosages for the Ivermectin Pour On are as follows:
1 drop - OEGB sized small bantam female
2 drops - OEGB sized small bantam male
3 drops - average bantams
4 drops - large bantams, small commercial fowl
5 drops - most commercial fowl, small giant hens
6 drops - giant breeds of chicken
They will look scruffy until their next molt. New birds are going to be nervous for a while. So keep the stress down around them. Use a ticking clock at night in the coop and play some soft classical music during the day on the radio. These help calm their nerves. Move slowly around your birds and don't try to pick them up for a while. Too scary. And go sit with them quietly on the ground on their level. Bring some goodies too so they know you have good intentions. Chickens learn by experience. So if all of your encounters are positive, they will warm up to you quicker.
They probably won't lay for a couple to a few weeks or until they feel comfortable. Put some fake eggs in the nest boxes so they know where you want them to lay and they will feel comfortable laying.
As for the bullying, Polish are often bullyied by all other chickens because they look different. The Top Hat looks funny to other chickens. So you may never be able to keep her with the others. For now, don't let them bully her and if she has open wounds, you will need to keep some neosporin (without the pain killer) on her wounds. Later after they are healed you can dab on some blu-kote with a q-tip to cover her bald spot so the others don't see it as the others will go after any wounds. Just keep on eye on them as you may need to keep her separate from the others permanently.
Good luck and welcome to our flock!