I just germinated some seeds as well. A tip to see if seeds are viable or not are to soak them in water overnight. They will float on top at first. The next morning poke the seeds that are still floating, seeds that sink have absorbed water and in my exerience, sprout. Seeds that still float should be given a full 24 hours of soaking then poked again to see if they sink. I've never had a seed sink that didn't sprout. And I've never had a floating seed sprout.

As for the light height, what kind of lights are those? I sprouted under a 4 bulb 48'' T5 system and started with them WAY too far away and my seedlings stretched 2 or 3 inched. I'd start at 12'' and work to about 6'' when the leaves show. Just make sure you have a fan blowing across your babies.

Happy growing!