If I wanted to make a complete setup for this in my house, would this have to be installed into the mainline in or at the sink/outside frost-free garden line? Also, what do I need to do this, is it all offered here on TOL?
If you do it in the mainline it may slow the flow of the water in your house. It's always best to just use it at the point where you will be watering. The parts needed to set this up will vary with how and where it will be installed. That being said, all f the parts needed are readily available at any larger hardware store.