For a small system like what you want you should raft using a piece of Styrofoam with holes in it and grow greens.

Set up a standard over the side filter for the goldies. I like aquaclear filters and you don't have to constantly buy replacement filters.

For the top tank you'll use a rubbermaid tub. Get a bulkhead fitting and install it about 3" from the top of the tub. Plumb a return line back to the fish tank. Cut the foam to fit in the top and cut out around the bulkhead fitting. This should end up floating when the tub fills to the overflow point.

Get a cheap small submersible fountain pump. Put it in the fish tank and run the discharge into the tub. Turn it on and water will circulate between the two tanks.

About once a week remove the styro and vacuum out the mulm that collects on the bottom. Let the water settle and return what water you can back to the fish tank. Keep the fish tank topped off.

Periodically rinse out the filter in the water you remove when cleaning out the mulm.

For the plants, cut some small holes in the foam, put in some rock wool and put some greens seed in them.

If you don't know about cycling a tank, read up on that. You need to get the fish stable before you start with the plants.