newbie help

I just ordered 2 Raspberry Pi's.
I plan on hooking them up to some bookshelf speakers for a multi-room audio solution.

From the RPi forums, I gathered that SqueezeLite is what I want to use for these.
First post so I can't post a URL but they linked to a thead on this slimdevices forum called "Announce: Squeezelite - a small headless squeezeplay emulator for linux (alsa only)"

Basically I want them to be dumb audio sinks.
I think the instructions are pretty straight forward for this.

The real question now... having no squeezebox knowledge or experience, what would I use to get music to play out of these?
I have a Linux workstation that stays on all the time.
My wife and I have Android phones, and we have a Nexus 7 Android tablet.

I'd imagine my scenario isn't that un-common.
I just need the bits and pieces to hook it all up.
I'd love to be able to play Pandora, iHeartRadio, Spotify, as well as local music from the server.

Please help me out and fill in the gaps here.

Thanks,
~Eric