I know there are a lot of threads floating around about cory cats, but I did a quick search and didn't see any that answered my specific questions.
1) Certain kinds of substrate are safer for their barbels; people say sand or smooth gravel. I would like to avoid sand because I am afraid it could damage the filter, and the cories might push food and whatnot down into the sand, and that would be difficult to vacuum out. So that leaves me with smooth gravel....Maybe I haven't looked closely enough, but all of the gravel I've noticed looks pretty much the same. Does anyone have a picture or a brand of gravel they would recommend for cories?
2) I'd like to add four and a betta to my 10 gallon tank. Should I add them one (or two) at a time so the bioload doesn't get thrown off? Or should I add all four at the same time so they don't get lonely?
3) People recommend quarantining new fish. How big of a quarantine container should cories have? Should it have substrate and/or hiding places, or should it be completely empty? If I stock multiple cories at the same time (depending on the answers to question 2!), can I quarantine them together, or should each have its own container? Do I need to heat the quarantine containers, or will a cory be ok with room temp for a week or so?
4) I am dealing with ich on a betta I got about two weeks ago. I am treating her with heat and salt, and she is improving. I know cories can't withstand salt, so if they end up with a disease like ich, how would I treat it? I know this question is more conditional than the others; hopefully the cories I end up getting will be healthy upon purchase, but dealing with it on my betta just got me wondering.
5) Cories are more sensitive to water parameters than bettas. Does this go for pH too? Mine is quite low. What is the ideal pH range for them?
[EDIT: already thought of another question!]
6) Should they be kept in groups of the same species, or will they still schoal/be happy if I have a couple of different species?
I'm sure I will have more questions as I get closer to stocking this 10g, I am a long way off. I was trying to cycle but it wasn't working. I'm going to try cycling again, and figured I may ask about this now, especially for question 1, so I can get cory-friendly substrate before I restart the cycle.