Cisco Auto QoS tagging through WAN connections

I have three locations with Cisco IP phones. Let's call them home, location 1 and location 2. All traffic comes back to the phone servers housed at the home location. I want to set up QoS for my phones and it looks like Auto QoS is the easiest way to do this.

I have my phone traffic broken out into it's own VLAN. After reading this documentation ( http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960x/software/15-0_2_EX/qos/configuration_guide/b_qos_152ex_2960-x_cg/b_qos_152ex_2960-x_cg_chapter_011.html#ID463 )
it looks like all I need to do is add 'auto qos voip cisco-phone' to my ports with phones plugged into them. As well as adding 'auto qos trust' to ports connecting to a "trust router or switch".

Attached is a rough diagram. For traffic flow, the default path for traffic between Home and Location 1 is the fiber between the switches. Between Location 1 and 2 the default path is the MPLS connection. And Home gets to Location 2 via Location 1.

I have several questions:

1) When everything's working, phone traffic flows like this: Phone Server---Home Core Switch---Location 1 Core Switch---Location 1 router---MPLS---Location 2 Core Switch. So I know I'm going to apply 'auto qos trust' to the interfaces connecting Home core switch and Location 1 Core Switch. But, how do I handle the MPLS connection and the Location 1 router? Would I just apply that command to the port that connects the Location 1 core switch and the router and also the interface on the Location 2 core switch that plugs into the MPLS? Could the router or the trip through the MPLS strip the QoS taggings off the traffic?

2) If any link is not working correctly, it can fail over via GRE tunnel through the internet to another location. Would I need to apply that 'auto qos trust' command on the ports that connect my core switches to the internet? (For Home and Location 1 this would be the ports connecting the core switches to the firewall directly I believe. For Location 2, that would the port connecting the core switch to the Router.)

Thanks in advance for anyways advice.
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