Details of Plants and Substrates used in this video

[jaks5021]

https://www.youtube.com/watch?v=-KGQ5fotrrg

I have recently seen an aquascaping video which really inspired me and you can watch it here: https://www.youtube.com/watch?v=-KGQ5fotrrg


However, the video is in Korean and I have some questions, appreciate if you can help me understand


However without the English I would appreciate if someone can give me answers to
1. @1:35 - is he closing the gaps using cotton?
2. @3:05 - What type of gravel is this?
3. @3:20 - what powdered gravel is he using?
4. @3:42 - what is the liquid he is adding into the gravel? is it some liquid fertilizer?
5. @4:22 - what type of soil is he using?
6. @4:56 - what liquid is he using? is it tank startup for recycling?
7. Appreciate if someone can tell me the names of the plants he has used.