Realistically, if you're going low light, low tech, you need really only what you have on hand for the most basic of plants. I had a lush 20 gallon filled with java fern, bolbitus, anubias, mosses, and crypts with just a single 18" t8 bulb that was about 2 years old. The gravel was huge river rock, with nothing special, and it was sparsely stocked. Everything was always happy and healthy, and I'm sad I didn't think to snap any pictures of it in it's prime. It grew slower the snot though.
A little more light will speed up the process significantly. If you can find them, and older 24-30" coralife twin t5no fixture could be perfect for what you're looking for. As I'm not seeing any of those readily available, then I'm going to suggest something like this.
For what you're trying to achieve, that should do you just fine.
Flourite is an excellent choice, although as others have said, it's extremely dusty. I've found my low light systems get the best growth and seem the most stable if I add about an inch of Miracle Grow Organic Potting Soil underneath the gravel. It really seems to bump up the growth of rooted plants and apart from the first few months, I really have no algae problems to speak of.
Good luck, take lots of pictures, and let us know how it goes!