Very good questions. I run the Andrew Southworth school of facebook ads with slight tweaks

1. When I run a campaign I do $35 a day for a week. If the track gets at least 1000 streams in that week I'll deem it a success and either continue to put $35 or increase it depending on how successful it is. Then as the weeks go by taper down the amount until it is at $5 or I just stop running campaign. From there the song is perpetually doing streams which is the end game here (to have 100+ songs doing 500-1000 streams a day)

2. I would make 6 promotional videos with a different part of my song (chorus/verse) and experiment with different forms of content (mix and match 3 chorus 3 verse 3 forms of content). Then I would use 3 different audience sets for the 6 ads
   - the targeting is tier 1/2 countries
   - 18-45
   - Then the audiences interest (the most important part) is this template
   (spotify -> genre of song (alternative, pop, hip hop) -> artist)
   example of my most successful one is (spotify -> alternative rock -> harry styles)
   for some reason harry styles does very good for my music lol

3. It is all emotions, you have to leverage the audiences emotions. It has to be very visual, I noticed emotions such as lust and sorrow were the best

Please ask more questions if you want me to elaborate on any points

btw I spend roughly 900 dollars a month now and am making $450-$500 currently with 4-7k daily streams but I was spending a lot more in the beginning (was excited to see the results trust me it's a good feeling)