First, the CR. The liquid logic outfitting is super comfortable. Secondly, it's not a true playboat, it's a free-runner or whatever you want to call it. The Biscuit is the playboat, so if you really like the CR go for it. Gets you down the river, and can still help you get basic play stuff down like surfing, stern squirts, cartwheels and loops, at least if you put enough effort into it. It can take you up to Class IV+ if you end up wanting to try creeking. Not that you'd want to paddle it constantly for that, but at least enough to figure out if creeking is for you.
As far as new vs. used goes, I say it depends how dedicated you are going to be. If you are really sure you are going to stick with it, I say buy new. Just be absolutely sure everything is 100% comfortable. That's where demoing boats before purchase comes in to play. The only reason I can think to buy a used kayak when you are starting out is if you can't afford both new gear and a new boat. If you have to choose between a used boat and new gear, or a new boat and used gear, get the former not the latter.