trying to finish setting up my tank

        I have quite a few questions for anyone experienced in plant
keeping. Currently I am setting up a 55 gallon paludarium and I am new to
the whole live plant scene. Ive been reading a lot on the net about live
plants and substrates but everyone seems to say something different. Also
there really aren't any great books in the LFS on setting up a planted tank.
The plant books I have really tell you very little in the way of substrate
options and hardly mention CO2 and ways to conserve it.

Tank specifications:
        A section of glass is siliconed from the front corner of the tank to
the back middle of the tank to give about 150 square inces of land area.
This leaves about 20 gallons of water. I bought a fluval 203 canister
filter for filtration and have a 2 bulb 4 foot shoplight with 2 full
spectrum fluorescent bulbs in it. Granted thats not a lot of light but I
want this tank more for practice than anything. There are a few low light
plants that I can keep from what I have been reading. Hopefully if all goes
well I want to buy a 75 gallon for a planted discus tank if I can get the
hang of keeping plants alive for more than a few months.

Questions:
        What substrate should I keep under the gravel for plant nutrients.
I have been thinking about laterite and tetra initial sticks near the roots.
Tetra also makes a bottle of trace element additives that I was planning on
using according to specifications also. Does this sound like it will work
or is there a better product or cheaper way of doing it?
        Also I am wondering about CO2 concentrations. The return tube of
the fluval will be positioned above a piece of tall driftwood (which is at a
slight angle leading from the top of the 55 to the water) which will direct
the water down into the water section.   For the moment I do not plan on
adding CO2 artificially. From everyone elses experiences will this be too
much water disturbance, therefore causing too much CO2 loss. By my
estimates this waterfall will disturb the water only a bit more than an
outside power filter where the water falls down from return. If this will
be bad for CO2 concentrations I was thinking of using the yeast method to
add CO2 and using the fluval filter as my reactor(this was my main reason for buying it).
        One last question was how I can reduce the hardness of my water to
an acceptable level. Being from the Wilkes Barre area of Northeast PA and
using well water my options are somewhat limited. Although I haven't tested
it myself I know that it is extremely hard and has a pH around 7.5. Reverse
Osmosis is out of the question for the moment. The local aquarium shop sells large bottles of a product I think was called tank soft which I was thinking of using. Does
anyone have any experience with this? How exactly does this stuff reduce
the hardness anyway. I am assuming for the moment that it softens the water
through precipitation. From what I understand this lower pH should also help to keep the levels of CO2 higher. Is this correct??

Once I figure out some answers to these questions I can finish the tank so
any help anyone can give me would be appreciated. I hope these questions aren't too often asked in this forum. I really just want to do this right from the start.

Tkanks for any help, john