One tip that I'd like to share is please don't rely on the mite/red mite powders to deal with any mite problems. I lost a hen to parasites in spite of using this powder.
Use flubenvet to deal with worms and you can also use kitten strength frontline to deal with external parasites, but weigh the bird before you apply it. It's not licensed for use on birds, but the vet will probably prescribe if you ask.
You can also get an Ivermectin Spray which deals with both the worms and mites - you get this from the vet too and should have the birds weighed before use as it's quite powerful.
Parasites can easily kill hens and cause great debilitation and loss of condition which leaves them susceptible to infection, so they must be dealt with effectively.
I use a hand held steam cleaner to get into all the hiding places in the coop to prevent red mite. I then use the powder in any bedding - that's all it's good for really.
If any chicken starts to go off its food and has a hunched up appearance with messy poop, then it may be coccidiosis - I use Coxoid to deal with this - you can buy it in small quantities. A chicken with coccidiosis will pass greasy poops and may have a sore bottom - they will also drink a lot of water.
Never use hay for bedding.
Apple Cider Vinegar in the water improves digestive health and also prevents worms.
I use a product called Orego Stim which is an oregano based liquid and this improves digestive health and also reduces the poop smell and quantity.
Treats should be fed sparingly, but can include: cooked rice, couscous, pasta, sweetcorn, mixed veg, porridge and ready brek in the winter.
Natural yoghurt can improve crop health and digestion.
Olive oil can help with digestive/crop problems.
Scaly leg mite is treated with the ivermectin spray and then use sudocrem on the legs/feet to get them back to condition.
www.thepoultrygarden.com/phpbb/index.php
There's lots of information here and if you want to join, the people are friendly and always happy to give advice.
Congratulations on getting your birds soon. They're a never ending source of fun and amusement. My light sussex got into the lounge two days ago and made itself at home on one of the comfy chairs.