Yeah, it can be kind of overwhelming at first. For now I think you can just go through the story until you feel like you have a good team, do some strike missions occasionally to get more characters (these rotate daily), and just experiment with the game in general. Most of the Dokkan events aren't necessary until you've completed the story on all difficulties (although they do help a bit), and they require really good teams, which you might not have ready until rank 120+.
Yeah get the free SSR and pray for Goku or Piccolo since Gohan sucks. Try for Gogeta but don't spend more than 200 stones on the banner.
You don't need 10 Omega Shenrons. There is this unit called Elder Kai ritual which can up the SA of a unit by 1 or Santa Roshi but thats only for the Christmas time.
Thank you guys!
I'm rolling through story mode and will soon do some pulls.
I'll report back with the progress and, probably, more questions lol
Thanks again! ^^