I'm a little tardy to the party on this one.
I have painted tons of poplar in the past couple of decades, and have always considered it to be a good paint grade species.
Lately we have been painting maple cabinets, alot, and maple is very nice because the grain broadcasts very little, it is hard, and allows great primer adhesion.
For primer, as Tom notes, I prefer W&W by SW, and Tom is right, it is not a drywall primer. It is the leader of the pack in latex interior wood primers.