I agree. WBR control is probably the only viable non-blue control archetype here, thanks in no small part to its army of planeswalkers. Olivia Voldaren helps, too!
I fully agree. The planeswalker options coupled with strong spot and mass removal make WB and WBR control possible.
I've recently moved Spike Jester to make room for Olivia. I felt that I had enough red and black aggro 2-drops already and also wanted to support control outside of blue and she does a great job at it (as long as you had the mana to support her).
Vampire Nighthawk and Exalted Angel are awesome creatures for WB control as they come down early enough to fend off attackers and start keep your life total at healthy levels. I'd love to see another strong 3-drop with Lifelink for either W or B soon though!