Onyx sand is a great choice. I bought 7 bags for my 72g and only used 6. It is great. For your tank, I would recommend getting 6 bags, you will only need 5, but 6 if you want to have one area higher than the other or something like that.
I would also go to home depot and get a 2 bulb shoplight. I got one about a month and a half ago for about $16, and I went back yesterday and got another one for less than $7. As for the bulbs, I wouldn't recommend getting the "aquarium" bulbs as there is no information on them and they cost more. They are the same as the other bulbs, but since they say "aquarium", people assume that they should buy them. I have two 5000K(natural daylight) and two 6500K(daylight delux) bulbs for a total of about $15.
About the food, you don't need any, they just help the plants along, but again, they are not a necessity. I would recommend using carbon dioxide for them. People have CO2 systems that cost a few hundred, but other people like me have do it yourself CO2. All it is is a two liter bottle with water, yeast, baking soda, and sugar. This is how it is done. Fill a 2 liter bottle half way with warm water. Add 1- 1&1/2 cups of sugar, 1 teaspoon of yeast, and a pinch of baking soda. Shake is up. Get some air tubing and make a hole in the middle of the bottle cap the width of the tubing. Insert the tub about an inch or so in the cap and seal it with super glue on both sides. Wait for the glue to dry. On the other end of the tube, put an air stone and put it in your tank by the bottom. Put the cap on the bottle and wait for the bubbles to start comming up. This will last for about two weeks.