Can I IM a buddy privately - not in a chat room

Yes, you can--here's how:

Add people as buddies when you see them in the chat room, then when they're online, if they have their own "My Chat Buddies" page open, they will show up in your "My Profile - My Chat Profile - My Chat Buddies" list, and you can chat privately if you want.

For now your buddies only appear if they have their own "My Chat Buddies" page open too. In the future we may get it to work where they don't have to have that page open for you to initiate a chat with them--we're working on it and making progress.