The first part of the question was, does it matter how many watts a given sub has, and the answer is yes - providing you have chosen a sub that is capable of meeting your desired output for your room size. The wattage isn't quite as important as the amount of output a given sub has. How large your room is will factor into how well a given sub will fill it.
The second question was can he hook up 2 subs, and the answer is yes to that also.