The speakers are connected to the ports labelled Speakers, below the USB port. Each speaker requires 2 wires, one each for positive and negative terminals. These wires carry electricity as well as audio signal. So speakers don't need any other cables.
Speakers are usually connected using bare wires, no separate connectors are necessary, though, you can use banana plugs for convenience. For connecting speakers, you can use regular electric wires or specialised speaker wires. I'm using 2.5 sq. mm. finolex cable for front and center and 1.5 sq. mm. polycab cable for the surround speakers. Specialised speaker cables can be more expensive. What you need to ensure is that you use 100% copper cables for good signal quality. Both Polycab and Finolex are very high quality cables.
It's less building and more like copying some files to a memory card and putting it in the Raspberry Pi. Volumio image is ready to go, you just need to set up the wi-fi network and point it to your library. I am using it for local streaming only, from my NAS. It does not support spotify free tier, so I use Echo flex for that. No support for Gaana or Saavn though, unfortunately.
