Blogging is not the same as it used to be a couple of years back. It's much harder now to rank a site with a brand-new domain.
1. It will take anywhere from 3-6 months or even longer up to 9 months to get a site where you can generate substantial traffic. You can get AdSense approval much earlier but that won't mean anything if you can't get at least a few dollars.
2. Again, you need to be patient. If you make $3 a day, you will make around $100/ month. It will take around 6-9 months or even more if your site is not ranked as expected.
3. Keyword research is important, however, I am afraid it won't cut it. You will have to manually build links as many as you can. But to get significant results, you will have to get links from PBN, Niche edits, and Guest posts. And that will require a good amount of money. You can even create your own PBN, again it will require money to set it up and maintain.