It's a side mission to raise cash. You keep getting the calls twice a week until out of SF (or at least that's where it stopped for me). You don't have to do it to progress in the game, but it's a fun extra.
Subtitles can be turned on in the display part of the menu if you're having trouble understanding the cut scenes.
I'm guessing 25hrs playing time.
What are the pictures and horseshoes you have to get to 1000% the game? Is it explained in a later mission? And does it unlock stuff like before?