freshwater planted aquarium...beginner

Question
Hello.
I have a 55 gallon freshwater aquarium, with the dimensions of 48" long x 12" wide x 21" high.  For lighting I have two 18" long Aqua-Glows that are 15W each.  My filter is a Top Fin 60 power filter.  I have two corys and one Afircan Dwarf Frog in the tank as of now.

pH: 8.5, chlorine: 0, total hardness: 120ppm, GH: 120, KH: 240, ammonia: .25 ppm, nitrite: 0 ppm, nitrate: 80 ppm

So the rule for lighting is 1-2 watts per gallon. For me that would be a wopping 110 watts!  What would I do for lighting in this case?
I have read that flourite is a great substrate for live plants.  I read that you can blend it with gravel, but just make sure the mixture is 50% gravel and 50% flourite. Does that work?
Is fertilizer necessary? Some people say that you can do without.  What do you reommend?
Are there chemicals I can add to the water for CO2?
I also read that you need to add nutrients. I know LEaf Zone is good for macro. I heard Flourish is good for micro.  Should I get Flourish or Flourish Iron?
Platys require pH between 7 and 8.5 don't they? And plants can't handel hard water.  So would I not be able to keep platys?I see photos of platys in planted tanks all the time, so would I jsut keep the pH at 7 to make the fish and plants happy?

Thanks!

Answer
It's going to take me a little time to research all of this. I'm not the best with CO2 systems. Did your tank come with a light?  I have heard of flourite being mixed with gravel before so yes I think that works. I'm not sure...about the Flourish I have never heard of that brand before. But Flourish iron sounds better as iron is good for the plants.  Platy's can live in normal PH conditions I have some in my tank with lower PH.  You might want to put just one in and see what happens. Fish sometimes can amaze you.  But if the corys are doing ok you should be ok with a Platy.