Lice or Mites? How doe you tell?

[dawnangel]

Is what i am dealing with lice or mites. Barred rock has nasty pasty butt, but also what looks like colonies of eggs or something on the feathers around her vent. Might be preventing her from laying, as I have gotten 2 eggs only for a flock of 4. My RIR hen also has a patch of missing feathers on her butt, and my little ameracuana actually had a white bug crawling along her skin. I know I need to clear, clean and replace my coop bedding, and spray or dust. I don't know what to use and my local feed store has something called python dust, does anyone know if it's any good? I'd post some pictures but I don't have the time right now. Is this an infestation of lice or mites, what's the best thing to do, should I cut the colonies on her feathers off, I know not laying is a bad sign. lastly, will my cat get infested as well? Should I just treat for both lice and mites and get the whole mess out of the way.

Any help would be appreciated

Thanks