Bud – Growcoir should be fairly neutral in pH so I can't imagine that you would need to add lime. It should be noted, that unlike soil, growcoir does not have any significant nutrient value to it. It's used primarily as a soil amendment or as a soiless growing media. Are you fertilizing with anything right now?
I've got a couple LumaTek ballasts and wouldn't use anything else. The newest version has an unplugable cord which is a bonus and it's wrapped for RF noise. They also have the best warranty of all electronic ballasts, 5 years (I think). As far as which one is better, I'm not really sure. I have friends using FutureBrite's and they think their great.