Just on the topic of plants:
I've got a low-light tank with a sand substrate. I added a bundle of Hygrophila about a month ago and it has taken off in the tank, almost doubling in height. I found that Wisteria, while beautiful, is very messy and was hard to get to "take" to my tank. Crypts are always a good option. I ordered mine online (the company stripped them of leaves so all I got was root structures, and a week later they're 5cm tall and still growing.) Frill is great for a cheap plant to fill in empty spaces. I've got frill in both my low-light 46 gallon, and my low-light 5 gallon. My cories love Frill because it provides low-cover for them.
Keep in mind that your Golden Gourami will reach a size of 6" while the honey gourami will only reach a size of 3", the rtbs will be 7" and each of the upside down cats will be 3-4". Depending on your tank size, they may grow too large to live comfortably in your tank.
As the upside down cat is a schooling fish, they're more comfortable in larger groups. While three would work, if you could get more in your tank, it would be better for them. What is your tank size?