One foot candle is one lumen projected on one square foot of area.
Start with the "initial lumens" of a bulb - a reasonable rule-of-thumb is that T12 fluroescents put out about 40 lumens per watt, while T8, T5, and CFLs put out about 90.
That means that the 28W CFL will have about 28 x 90 = 2520 initial lumens. Keep in mind that it isd radiating in all directions from the spiral tube, with some of it lost to the inside of the coil. With a decent reflector, you can bound most of it toward the plants, but I'll wish you "good luck" trying to estimate what the intensity is at the leaves.
Concerning red or blue affecting what - the fact is the plants need both, and a 2700°K bulbs really doesn't provide much of either - it's just heavier in the red end.
Take a look at these articles to learn more:
Artifical Lighting
Artifical Lighting Intensity
Light Sources & Color Temperature
Threaded Mode
