ohhhhhhhhhhhhh man, slipon your just getting started, i can tell from your post you using a lot of common sense, which is good.
but.... science doesnt always make sense till you break it down.. kelvin is just a color rating and has no relavance to the NM of spectrum emitted here is a 5000k bulbs light spectrum
http://www.drsfostersmith.com/images/adinfo_florasun.jpg
as you can see a large spike at 460nm and 620 630 and 660 nm which are mostly not yellow but the blend of colors would make it appear yellow.
th first thing you want to learn is using lumens as a stand point, so anything in range between, 2000-4000 lumens in veg is adequate given you use the proper spectrum. lumens is a measure ment of what the eye can see, not what plants see. i use wattage per square ft personally.
second is kelvin is the most inaccurate way to measure color.