Yes, people keep talking in Hades. You will hear your own native tongue as the language barrier will be gone (this is not biblical yet, it's a result of research and personal experience).
Time-space is something humans never understand fully (as proven by today's science), so everything is possible at the presence of God. If God would like to make people talk from heaven to hell, He CAN (as a matter of His omnipotence)! Moreover, according to Paul's experience, he's in the third heaven when he couldn't even distinguish whether it's in body or out of body. I am not surprised if one can talk from heaven to hell. Both heaven and Hades are a matter of spaces.
Again, if that's what God wants, that you can look down from heaven to see that the worms won't die while the fire won't quench.
Yes, if God allows, you may hear the screams too. However, in a complete separation, no one has the interest to look at what's already outside God's realm. Or else, it won't be called a separation.
You have to taste yourself or ask those in such a burning hell to know. It's not happened yet. We as humans don't know the future.
Does size/space matter to God? Take a look at the universe and you shall know that space is never a problem.