At 12% i really wouldn't worry too much... but beyond 16 and max 18IMO. After these it's just gets harder and takes longer to shed it off.
The straight whey i say use post workout. I use 50g whey, 70g dextrose. Sometimes i'll resort to the sweets postworkout when i really can't control hunger. All other times i would say combine the different kinds of whey, w/ cassein and a little soy. Soy will decrease absorption time by 30%. Good to keep you anabolic longer.
About your workout routine. I like the first one a lot better. When you work out 2 big muscles in one day like legs and back as you mentioned in second routine you will comprimise growth in one of them. Plus you want the most blood to be circulated in one area, not dispersed to back, bis, and legs. Keep it focused and concentrated in certain areas like you had in first routine.