Cory Cat issues...or not

[ed.alfonso]

I need some guidance on a few issues with Corydoras & husbandry. As my collection grows I am finding I want to learn more & more. I have been lucky to have come across some beautiful fish and when ever I find a fish has died I need to know why & could I have done something to prevent that. Which has led to the following questions
What Web sites do you find have the best information on keeping Cory Catfish and having them thrive? I have been referencing books I have collected over the past 40+years but I'm sure they are out of date.
When quarantining new fish, is it best to treat with meds to knock out any potential bacteria & parasites? What are recommended meds?
When fish get sick, how is the illness & cause identified? Or are you taking best guess based on observation & past experience or information from research? Again, is there a combination of meds and preventative measures that are used to help reduce fish loss?
Is it worth getting a microscope (I'm leaning in that direction) & learning how to collect samples to identify issues? What is best type of microscope?
What types of food ? I use a varied assortment from Repashy, freeze dried tubifex worms, frozen brine shrimp, daphnia, frozen blood worms as well as different types of pellets and flake foods. Live black worms, white worms & grindle worms. I have read & heard some folks do not like to use live black worms due to potential problems. How do you deworm the black worms?
I have been in the hobby most of my life and have kept & breed dwarf cichlids for a long time, I have always liked having corys. Now I find my self with an ever expanding fish room and a desire to know more & more.
Thanks in advance for your suggestions & help!!
Regards,
Ed