Pitching a stock for interview

I'm interning this year in the back office of a BB, but I'd really like to interview this fall for an entry level position (graduating undergrad in 2010) in research at the BB, either equity or credit. I've spoken to some ppl within the division and I know I will most likely be asked to pitch a stock. Exactly what do I need to talk about and how in-depth do I need to go (how much time should a pitch take)? Is it acceptable to pitch the BB's stock?

Also, I have been considering signing up for the CFA exam in an attempt to distinguish myself and prove my interest in the field. But before I drop $1000+ on the required fees, I'd like to know: is this overkill? Should I wait until I get an interview or get hired to register? Do most people go for the CFA while in undergrad or is it more common to do it with a few year's experience?