Just wondering whether your site uses a standard theme? A possible reason for the theme and talk options not displaying is because they have been hidden in a custom theme. Hardly anything has changed in the Chat activity in recent versions, so it should look the same in 3.5 as it does in 3.8.
I actually find the theme button and the talk and bleep options not so helpful however!
If you try changing theme, it throws you out of the chat session and when you re-join, you can't see previous chat messages.
The talk option looks like a way of sending a message to just one user, but what it actually does is send a message prefixed with the user's name.