Answer:
A) Electricity costs are considered fixed costs because the company must pay them regardless of the volume of output. The cost of electricity varies from month to month since the consumption level is not always exactly the same, e.g. one day you turn on your computer 10 minutes earlier and your electric bill will increase a few cents. But generally speaking, the electric bill varies very little and it is fairly constant around certain average level.
B) A business's bottom line is net profits, and net profits are calculated by subtracting fixed costs and variable costs from total revenue (and taxes of course). If the fixed costs decrease, your net profit will increase.