Well from I have read, 6,500K to 10,000k of kelvin lights are ok for planted aquairums. I have 2 small 10,000k Compact flouresent light bulbs on a 10 gallon and everything grows fine. I don't know about the VHO lights being ok. One major problem would be the distance from the bottom of the tank to the top. Some plants might have problems if you get a jungle in there( some plants might get less light than other plants).
There is many aquatic substrates out there from play sand to Aqua soil.
Flourite-Good substrate, good for beginners, some what expensive if you buy all flourite, and you have to wash it very well and let it dry. There is red, black, and normal as well in sand and chips.
Eco-complete-Black, from the Amazon, expensive and rare to find sometimes, light weight, fine with plants from what i read about it.
Aquasoil- greatest substrate for plants by some( I'm not a ADA buyer so people are going to add more to this one) and its expesive,c but very good.
Play sand- small grained, cloudy, not very rich in nutrients, and can compact.
Some substrates that are most commonly used.

You would need compressed CO2 for such as big aquarium.
Discus would need very high temperatetures because they live in the sunny side of the Amazon

so your plants would have to be able to live through high temperatures The plant finder on top top of the page would help you alot in this situation.
My comments.