No there is no roaming within Canada or local calling areas. You're good anywhere in the country. Only thing is if people in SK call you they could face long distance charges if it's not included in whatever plan they have.
This would depend on whether you have a Canada-wide plan or not. If you don't have a Canada-wide plan, then you are charged for long distance when you make or receive calls outside of your local calling area. Not sure what you mean by data increase, can you elaborate?