BTU's

[hankhill]

i have a 32'x 28' with 7' ceiling. this space has some heat from main furnace in house but i would like to add a gas stove for more heat as i live down there. gas pipe connection already there. approx how many btu's do i need?
also, i would also like to know if vent-free stove is a good choice and if anyone can reccomend a good product?