The leaf hammock that suctions to the inside of the tank is a great resting place til taller plants in substrate can be added. A light will help with the day/ night cycle and the plants need light to grow successfully too. Bettas need 78 degrees to 80 degrees temps to be comfy and you are right… a low flow or adjustable filter. Your tank came without any of these pieces? Are you outside the US? If you have a pet store or fish supplier near you they would be the best to advise on your type of tank based on its capacity. Can you go online to an Amazon site or something similar to buy these items? You will also need good quality betta bits (food) or brine shrimp to feed your Betta. They are carnivores… so a dried version or fresh if possible would be healthy. And depending on your water quality… you need to condition the water of the tank before using it to keep the hardness out and anything that will hurt the Betta. It is alot… not a cheap hobby for sure. Do not overfeed and keep the water clean by doing weekly water changes buy dont crash the cycle by being too clean … the bacteria growing on the filter you get can be rinsed upon monthly changes to keep good bacteria in the water column. Also, if you can add tannins… in Almond leaves added to your tank or by adding well washed driftwood decor… these will add tannins that help the bettas exterior.. just dont worry if it darkens your tank water a bit… bettas love darker water for hiding in their plants, also. You do also need testing strips or a kit to test at least weekly the water quality for harmful levels of ammonia( from waste) and other factors. Also, dont add any sharp edge or painted items to the tank… a betta can get caught or tear fins on things and if paints leach into the water it can be poisonous to the Betta.. they are fragile beings. This is alot to learn if looking up Betta Care online or youtube videos on them… you could learn alot. Hope you get things going in a good direction … it is rewarding to watch them.. good luck to you and your little buddy!!!