I've ridden 0/0 before if that's ultimately the most comfortable for you then have at it. I think in the long run you'll get excessive torque on your leading knee but if it works for you, it works.
Otherwise calf pain could be due to a few reasons first and most obvious is that you're using them more intensely than you normally due, (i.e., you're just not yet in good "boarding" shape early in the season). Another obvious culprit is forward lean. On most (all?) bindings you should have the ability to relax the forward lean. I'd turn it down to 0 or as close to 0 as it allows. You don't need it, and that will alleviate stress on your calf muscles.