Quite a few options you have, but it would depend on if you are going to keep one of the Gouramis or not.
If so, you could keep a small school, 5-6, of most tetra species. Without the Gourami you may be able to bump that number up one or two. You could also keep 4 or so Pygmy corys providing you have none sharp gravel/sand substrate.
Glofish are genetically altered Zebra Danios and from my understanding tend to be nippy so I wouldn't keep them with the Gourami as you couldn't bump the school up enough to spread out aggression and they would likely nip at the Gourami. Perhaps around 5 by themselves would be alright in a 10.
You could keep a few male guppies too Three I think would be alright with the Gourami, 5 without.(unless you want fry, then 1 male+3 female guppies but be prepared for a LOT of fry).
Do a little googling, find some small fish species you really like, learn as much about it as you can, then come ask any questions and I along with many others I'm sure would be more then happy to help
I don't know much about aquarium restoration so not sure how much I can help in that area, sorry.