Lot's of good stuff there Vib.

First of all you have some equipment malfunctions. The buzzing sound should be found. It could be that your bridge is too low and the string is vibrating right on the fingerboard. It could also be a loose fine tuner or something. Very hard to tell from our end.

Try pressing a little less with your bow arm. The scratchy sound comes from pressing with too little speed so when you aren't moving the bow anymore you should be releasing the pressure.
It's great to have a powerful sound but also nice to play soft as well. Figure out when you would want to climax and how you want to start and finish each phrase.

I like your project and the piece. Look forward to the next post.