1995 Nissan Micra starting problem

1995 Nissan Micra 1000 mileage: 36,000. I have two questions: 1) For the last two years I have found increasing deposits of white powder around my battery terminal. What could be causing this? 2) Twice in the last two months when I have gone to start my car for the first time it has crunched and not started as if the starter motor is not engaged properly. How can this problem be solved? Could this problem be related to the battery problem? Thank you