Why are you so convinced they had canker? There are several other conditions which present very similar to it, the only way to tell is lab testing. As for the neurological signs, have you tried using the chicken symptom checker tool? http://www.poultrydvm.com/views/symptoms.php
Please bring him to see a vet. Dogs carry a bacteria in their mouth which is deadly to chickens. He needs antibiotics or he will die. Here is a directory of vets who see chickens - http://www.poultrydvm.com/poultry-vets.php
That is really odd that an 8 month old rooster suddenly died out of the blue like that for no apparent reason. You might want to consider getting a necropsy done so you can figure out what happened and why he died -...
Please please please take her to see a vet. Dogs carry lots of bacteria in their mouth, and she will die without antibiotics - http://www.poultrydvm.com/poultry-vets.php
Yes, you should 100%. Not only will it help your coop stay warmer in the winter but it will also keep them cooler in the summer. Here is some tips on what to use -
It depends on which mites they are. If they're mites at all. Here is a good infographic on how to figure it out - http://www.poultrydvm.com/featured-infographic/identifying-common-ectoparasites-of-backyard-poultry
The big key is looking at the first 3 ingredients listed on the feed tag. Never get feed that doesn't specifically state what it is in the feed. However if you want a useful tool to make comparisons like this, here is a link to a feed comparison tool - http://www.poultrydvm.com/feeds.php
Yes. Bring him to the vet immediately. Dogs carry lots of bacteria in their mouths which are deadly to chickens. He probably needs antibiotics before sepsis kicks in. Here is a case story about it - http://www.poultrydvm.com/cases/goldie for your reference. And a directory of vets who see...
Elector PSP does not kill the lice or the nits. It only works on mites. Here is more info about lice for your reference - http://www.poultrydvm.com/condition/lice
Unless its on this list, and isn't contaminated with mold, rotting or otherwise in poor condition, it is usually ok for chickens - http://www.chickendvm.com/toxic.php
There are other things besides Mareks which can cause weight loss. Have you tried using the chicken symptom checker tool yet? http://www.poultrydvm.com/views/symptoms.php
Its too bad you didn't check on poultryDVM before, you could have given her activated charcoal..not its too late - http://www.chickendvm.com/poisonous/avocado
Have you tried using the chicken symptom checker tool? http://www.poultrydvm.com/views/symptoms.php - It might help you narrow down the possibilities..
Add enrichment items to your flock, to help take their minds off pecking each other. Here is a good infographic with ideas - http://www.poultrydvm.com/featured-infographic/environmental-enrichment-for-poultry
It sorta sounds canine like to me, but you could always try the poultry predator identifier tool to double check - http://www.poultrydvm.com/predator-identifier.php