cool, you'll have to take pictures of it after it's set up so we all can see!
Put two goldies in, no one likes being alone
On plants, hmmm, it's so small I'm not sure. The sides are clear which means you want it to look cool down below water as it does above. Here's an idea.
Get a large clear glass vase and some of those glass marbles then get a water cana lily


If you buy the cana online it will come bare root, if you buy it at a nursery where you live it will most likely be in it's pot. You want it bare root so clean off all the dirt from the roots and stick it in the glass vase and pour in the marbles. This will be your tall plant.
Get a smaller glass bowl or something like that, maybe a small clear glass flower pot. Get an oxygenator like Ambulia or hornwart


put this plant in the glass bowl or pot pour in some glass marbles to hold it there. Now you can also place in a water poppy because they don't get very big, and they look like miniature lilies

and they will cover the top, or you could go with Water Hyacinth which will look great floating on top.


wow, after thinking about this I may want to buy one of those tanks! I think it'd look cool on my patio.
Well there are my suggestions. Remember, you don't have to put your pond plants in soil, they'll live just fine without. Since you have fish in your little pond their waste produces ammonia which goes to nitrites then to nitrates which is plant food!
Please post some pictures when you get it set up.
Scott