My only concern with plywood is it creates a natural environment for molds/bacteria/etc to grow on. With what you're growing I feel pretty sure the plywood will be ample. maybe even overkill. have you considered styrofoam insulation?
If its a small aquarium (maybe 12"-14" across) that'd probably work.
Also, make sure to paint the glass light proof to discourage algae growth.
As for the drowning the roots issue, just make sure you aerate the roots the same way you would fish. With a waterfall or air stones.

The plywood will not hold up. The water will dissolve the glue, plus it will swell, warp, and grow mold. Foil-faced styrofoam insulation is a much better idea.

I agree, styro is the way to go. Plywood will suck up water vapor and warp. Plus, styro is way reusable. You can clean algae on foam without harming it.

Styro or plastic.

Keep wood out of any equation involving liquid, soil, and potential fungus/bugs.

Here is a link that might be useful: My Indoor Growing Adventure

Don't use plywood. It will rot and become a breeding ground for bacteria. I would use sheets of acrylic that you can get at a hardware store. make sure you paint your tank and lid either black or white so that no light gets through.

Make sure you have an airstone and you won't have to worry about drowning them. Most aquarium or pet stores have a decent selection. The more dissolved oxygen in the water the better.

For a noobie, maybe try this hydroponic system. This package comes with everything you need to get started: http://www.ehydroponicssystems.com/hydroponics/rainforest-66-6-site/

Here is a link that might be useful: ehydroponicssystems.com

All:
I am uploading a pic of the system...it still needs some mylar, I think an emergency blanket it the ticket...Waiting for my first sprouts germinate....any comments welcome

Not bad at all!

Mylar is overrated. A white wall is almost as good. When your plants get past seedling stage, you will probably want more light. You'll also want a fan to blow gently across the plants.

Looks good. What did you use for hangers and what are the wattages of the bulbs?

Well done!

Here is a link that might be useful: My Indoor Growing Adventure

the lights x2 40watt, 1600lumens, T12s, the hangers are simple eye hooks in the ceiling and some small chain.