Sort:  

Do I need to wait until after the Hard Fork to begin using CC on my posts?
I am also using hive-106444 account and hive-179017 account for the Communities that I am administrator for. Does it make sense to set up CC on those accounts?

you do not need to wait. You can use the CC Tag anytime ;)

You can try to fill your community accounts with CC. I would say in general that it works from a technical point of view!

Can I transfer CC to the community accounts from my main account, if I decide I want to do that?