You can get a 300 watt security light at walmart for about 10 bucks. That will get you through a couple weeks after that you are going to prolly want to switch to something like this https://www.rollitup.org/general-marijuana-growing/2810-home-depot-light-bulbs.html at least or at best 1000w HPS with a nice ballast for indoor growing.
thats a very vague and indescript question. its not the wattage that matters, its the bulb type. a 42w compact fluoro will put out a shitload more light (in lumens) than your 250w heat lamp. when growing cannabis, the more watts the better, to an extent. a 1000 watt HPS/MH bulb is useless if you cant evacuate the heat it radiates. so it really depends on your fiscal and growing space situation.
What the fuck are you talking about? That one 42 watt cfl could grow 2 plants with the right reflector and various pruning techs. I have seen it done with alot less than that!