How much information is Facebook Home tracking through the device it is installed on?

I haven't used it or plan on using it but I'm just wondering how it actually integrates in peoples devices.

I would assume that as it is facebook they will be leeching as much info off a device as possible but what if I don't have it on my device but SMS back and forth with someone who does have it? Will it be harvesting everything I am saying to the other person through their device? Similarly will it be sending data about who calls people and when?

I've seen a lot of talk about it but no mention of how much data it is accessing from a device.