Hello,
There are no guns in the game :D at least not that I'm aware of. Maybe later in the story-line.
Yes you run into police a lot in this game and you have to run from them. The best way is jumping over walls.
You can hire your own drug dealers that deal drugs for you on neighborhoods.
There is a story-line in the game and you do missions for cartel but the game has some bugs and you can't yet finish it. I hope they'll fix it soon.