This is the appropriate place to post suggestions.
1. Roar is probably using some other window style (popup, tooltip), so the timeout option doesn't apply to it. Not sure if it can be used for the chat window. But i'm not a developer myself. Looking through the Roar's source i see RoarPanel.popupWindow function used.
3. As a workaround you can set it to say 30000000 and it would stay almost indefinitely. Though i haven't tested, but it saves such a value. Of course, having it using a 0 for this would be more convenient/understandable. 
SPARK-1595. Though Roar's developer is not active in the community/project anymore, so i can't say when/whether anyone will look into this.
4. This sound too complex for a simple chatting program and a popup plugin (and even above the xmpp specifications: sending additional type information with the message). Having different settings for group chat and general chats sounds reasonable. 
SPARK-1596