Java moss, fern, hornwort,elodia(anacharis), hygrophilla sperma,are some I recommend. These are mostly feed off your water and not the substrate. Making the plant tabs very not needed.
There are some plant tabs that have too high of the middle number which is phosphates. Plant tabs by aquarium pharms I believe are one of these . Plant spikes and Jobe spikes are much better, but I don't feel you need this yet.
Buffering I feel is only really needed when you have Co2 added. Otherwise , don't mess with the PH. Usually you have enough Gh to buffer anyways.
If your PH is below 7, you probebly have a low GH and that isn't so bad cause your in the clear with the fish waste because it is in the form of ammonium(instead of ammonia). Plants like this, and also live of of nitrates when not ammonia/ammoinium is present.
Remeber to change the florescents every 10 to 12 monthes. The bulb starts to die and promote algae.
I honestly dont reccomend an Amazon with the lighting you have. I feel amazons require more light than a low level plant, and their root system requires deep gravel.
Also like said, they can grow quite big.
I wouldn't add too much ferts to the water with low light plants. Especially adding them one at a time. You will never use what is in the water (according to the dosages on the bottle) until you get a pretty stocked tank.
Of course this is my opinion.
How many watts are on that eclipse anyway?