Thanks for reading this, I read it all the way through also and I can't beleive how bare it looked when I started. I use a gallon jar of DIY CO2 mix and diffuse it via a CO2 ladder and then into a powerhead that chops up the bubbles that make it through the ladder. I dose 2.5 ml of Seachem's Flourish every Wednesday and Sundays after a 30% water change. The plant that you're talking about is Pennywort, the one with the pale-green, wide leaves. I've found out that if I sink a leaf into the sand and cover it, it stays there rooted to the ground.
Glad to read it, I'm going to convert your schedule into a 55g and try it for a while. Nice work!