That depends on what you're going for. Some plants do better in low lights and some plants will grow too fast and quickly overtake the tank with too much light. Some fishes are also sensitive to bright lights so you'll need to have plenty of shaded areas for them.
You'll also have to be careful with the heat issue coming from that much wattage, but there are plenty of people that have 4watt per gallon tanks.
regarding the kind of bulbs you have, a simple test is to look at the color. if the light is similar to what you have in a living room (a soft yellowish tint) then its a 26,000k soft white bulb. If its very white, like in many bathrooms or hospital, then its 50,000-65,000k "daylight" bulbs. If it has a bluish tint to it, its a cool white or actinic bulb. If its purplish or pinkish, then its an aquarium light designed for plants.
