Got some stereo wiring questions - Need some help.

Thanks for the info. The only reason that I am going from the front speakers is because I am actually mounting the sub under the drivers seat. I got a very small amplified sub from Kenwood (you audiofiles would probably be disgusted). It’s not going to be pushing out a ton of bass, but it will be good enough for me. I wanted to run the least number of wires possible and for the least amount of length.