Trying to figure this out

For rooted plants, you'll need a deep substrate--2 inches at least, IME. I like a mix of laterite/flourite and sand. Provides a variety of sizes, and helps the plants.

I think most mini-bows come with a filter in the hood? All of mine have, so I am not sure. If yours does not, there are several options. I prefer the HOB filters, like the AC mini, for small tanks--internal filters just take up too much space. Just about any kind of power filter will provide plenty of water movement--adding an additional pump could be way too much current.

Until you've gotten the hang of maintaining the tank, I would hold off on adding CO2. It's usually pretty easy, but in such a small system, a sudden pH drop could be lethal to your fish. Once you've got the system in balance, and know what your hardness/pH/CO2 is without supplementation, you can look into adding it. For all 3 of my small tanks, I've gotten very good growth without any supplemental CO2.

I have found that Water Sprite is a very easy plant to take care of. Like a lot of stem plants it doesn't really root, so substrate isn't very important. But light is. I assume that the mini bow has flourescent lights. If not then it will not be easy to grow plants in. Another easy plant is Java Fern which does root, butalso doesn't seem to need much of a substrate.

I like Water Sprite cause it is easy to find, grows well, and you just cut the top off when the bottom is looking ragged and the plant continues to grow. You can even cut off mature leaves and they will sprout a new plant.

Substrate

I would suggest 100% Flourite, then you won't need any additives for live plants. There's a 'red' Flourite and the 'original' or regular. The 'red' is too red for me. Regular Flourite looks natural.

Larger pebbles can make a tank look 'smaller.' A sand, or small gravel (like Flourite) will give the appearance of a larger aquarium and more natural looking. IMO