Hmmm, which is better? I don't think there's a right or wrong answer to that one... If you can't run then by no means don't run... Walking or elliptical? Some swear by one or the other... IMHO, both are good, both burn calories, both can be done at higher intensities and more incline... Try them both, do them both variety is a very good thing...
As for the calves, well I have a girlfriend that has super skinny calves and no matter what she does she cannot make them bigger, it's just genetic for her. I think once you lose weight you'll get a better idea if it's genetic or was just fat on top of muscle...
Sorry I can't be of more help
, but I hope this helped a bit ...