Work-Space-In-The-Home Expenses: Do we use the amounts paid for "Electricity, heat, and water" and "Internet" for the whole year or what was paid on monthly basis?

You would enter the total expense for the amount of time during the year that you were working from home, so if you worked at home for the full year, then you would enter the total expense for the full year.

You would put the amounts in the box that corresponds with what sales tax you paid on the expense. For example, if you live in Alberta, then you would be charged GST on your internet bill, so you would put that expense in the GST column.