At risk of making your night worse, I've thrown a few ideas down here - too much time on my hands tonight.
It's stuff I wish I'd known years ago when I started rescuing sickly cats, much of which I've learned from this forum.
Have a shuffle through this page:
http://www.fabcats.org/owners/mouth/info.htmlThere are definitions of most mouth problems, you can see better than we can what's happening, there may be a clue for you here.
The constant drooling will be contributing to her dehydration. Can you let down the kitten milk with a little water to help her fluid intake?
I would leave her stained fur until later, the preparations that deal with this might not be good for her right now.
Here it is, though:
http://www.vetuk.co.uk/eye-products-c-663/tear-stainum-remover-p-4805As for the poo in her ears, that's precisely what it will be, earmite poo is the black stuff she's clogged up with and needs to be removed. There are videos on line showing how to do this using cotton pads.
http://www.vetuk.co.uk/ear-products-c-8/cleanaural-cat-ear-cleaner-p-32The mites themselves usually need to be killed off using Canaural lotion that your vet will prescribe. Everyday for two weeks. She needs an effective flea treatment like Frontline to help kill of any mites that may not be directly inside the ear canal, and her surroundings will need to be treated with an insecticide like Indorex. Earmites are easily transmitted between animals, so this is quite important.
If she's had fleas and earmites she will certainly have worms. Your vet will advise when it is safe to administer worm and flea treatments, as she's so frail just now you need to be sure not to overload her with too many preparations, and they need to be done in order of priority. When you see the vet take a notepad with you and get him to order each of the treatments for you, so he may worm her for you, but advise leaving her for a few days before applying the flea treatment.
Please also bear in mind, if you are likely to ask for a blood test, insist this is done BEFORE the vet administers ANY anti-biotics, as these skew any results and mean you may be dosing her with ABs she doesn't actually need for weeks before you can get her tests done.
I will mention FIV here. If she is FIV positive, please don't freak out. Many false positives are found on the preliminary tests. If the secondary test is also positive, you need to come back to us for advice because this is not a dangerous condition and new research is disproving the old wives tales over and over. In fact, if my new intakes seem healthy I choose now NOT to test, because I know I would not treat them any differently if I knew they were FIV+ve or not. FIV is transmitted only by deep bite wound or direct transfer into the blood stream or sexual contact. It is not transferred by sharing food bowls, litter boxes or casual contact (cuddles).
FelV, however is a far more serious matter and as she is frail and sick already, I would ask for the FelV test.
This is a highly contagious and lethal condition that can be spread to other cats by the saliva and nasal secretions and has a longer shelf life outside the body - up to 2 days, so can be transmitted by shared water and food bowls, litter boxes and on human hands. If she has FelV there is little you can do for her, especially as she's already sick. Felv does not affect humans or dogs, however.
She is already showing some worrying symptoms and you do need the FelV test, as soon as you can.