Thoroughly read, then re-read that site. Then read these articles:
To answer your questions:
Regarding lights: Read the part of Rex's site on lighting. It is not about watts, but rather, lumens. It is harder to calculate lumens, so people made a general rule of 2 watts/gallon. However, if you read the article some more, this rule does not work for smaller tanks. Your tank may fit into this description. However, the type of plants you have determines how much light you need. Some plants do not need as much light. More light means more CO2 consumption, meaning you need to use Flourish Excel (not CO2, but a form of useable carbon), DIY CO2, or pressurized CO2, depending on your plants and your needs. More CO2 consumption means more nutrient consumption, meaning you need to dose fertilizer. Flood lights could potentially work, but they are usually not cost effective. The "hooded" fluorescent lights you are talking about may not be a good option, either, as I am assuming you are talking about the kind you find at petco. Do some research on color temperature and lighting intensity. Generally, 6700K is the accepted value for best color temp for planted tanks. It is not necessary to have exactly this value. Try to avoid "actinic" lights meant for reefs; they do not work very well for plants. Do a search for coralife, TEK, or go to ahsupply.com. Those are good examples of lights that ARE good for planted tanks.
On substrate: It is not necessary to use fancy substrates. Many people grow plants in plain sand and do fine. However, it is not easy, and I'd bet those people are fairly experienced. If you are doing 10 gallons, I would also recommend eco-complete. It sounds like you want this done on a budget, so I would not recommend ADA Aquasoil. Keep in mind that most of the nutrients in your substrate will be gone within a few months; you are not necessarily paying for nutritious soil. In fact, ADA Aquasoil is probably one of if not the only substrate with nutrients in it already. Eco-complete is a good choice because it is already seeded with bacteria and also contains a good amount of trace minerals. There are cheaper options, but they require more info, are messier, and may not be worth it for you in the long run.
About heaters: Your heater is less for your plants and more for your fish. I would think that you already had a heater for your fish only tank. You should do research on what temperatures the fish you want to keep need. Then, you should buy a heater with a wattage that is appropriate for your tank size. Then you just set the temp, keep an eye on it (use a thermometer), and that's it. Buy a decent heater because they don't cost that much, and you don't want to cook your fish.
About your filter: You can do a planted tank with a HOB filter, but you won't have as intense growth as possible. With an HOB filter, you will only get equilibrium CO2 levels, usually around 3-4 ppm. Those with pressurized systems get about 25-30 ppm.
About fish: GBR's are very sensitive, so make sure to acclimate them very slowly. And by that, I mean drip acclimate. So, maybe like a drop every second or two, over an hour and a half to an hour. If you get a pair in a 10 gal, I would skip the tetras, because it is likely the rams will get aggressive when they breed, and in such a small space, the tetras would get harrassed and maybe killed. If you do get rams, remember that they will dig and may uproot your plants. It may be possible to prevent this by providing them with a cave.
Do a lot of research before you do anything, or you will just end up spending more money. You can start out low-tech and budget, but this hobby is addictive, and you will soon buy more and more stuff. Remember, you can go as budget as you want and you can still make it work, but once you get hooked on the good stuff, it's hard to go back. Enjoy!