Waitlisting is a DVC thing. Owners can be waitlisted if the nights they are booking with points aren't available, and if they become available, they get it.
As far as BCV vs BWV, so far as I am aware, all of the BCV rooms have at least one balcony. Some of them just fit two chairs and a table, and some are HUGE. I've had a 1BR with two smaller balconies, and I've had a studio with a balcony that seemed larger than the room. So the balcony size at BCV can vary a lot. I would consider more what view you would prefer. The views at BCV aren't as good for sitting for hours to watch the world go by as the views at BWV. Even though you can also see the parking lot, the pool view would probably be the most interesting at BCV. If you're booking with points at BWV, are you booking a Boardwalk view or not? That would be my first choice if you are spending a lot of time on the balcony.
Another thing to keep in mind is that if you plan to do any restaurant dining at your resort, you do have to go outdoors in the weather to get to the BW restaurants, while you can get to the YC/BC restaurants totally under cover. I know I don't dine out as much when I'm staying in a DVC unit, but it's still nice to be able to go to the restaurants and shops if I want to without getting soaked in the rain. Plus, I really like how close BCV is to Epcot, just for the dining possibilities. If you have an AP, it's no big deal to just pop into Epcot for lunch or dinner from BCV.
Of course, the actual units are pretty much identical, except for decor, so that's not so much of a deciding factor.