You’d have struggled to have chosen two more diametrically opposed choices! Argon’s have a reputation for being really, really stiff. As a first dabble in to carbon, the Krypton wouldn’t be my choice.
At the other end of the scale, you have a ti frame. I’ve no direct experience of the Planet X, but all the ti frames I’ve ridden have been too flexy for me.
To your other questions:
1. Salty, crappy muck through the winter can act like a fine abrasive which dulls the lacquer. I’ve ridden my carbon frame through two winters and it’s been fine apart from that.
2. Horses for courses. Personal preference more than anything else.
3. Good wheels are nice to ride on whether you’re training or racing. Ksyrium SL’s are probably a bit too nice to be running through the winter though.