First xml is a network definition file - as said earlier, they are one way for managing libvirt networking, which I do not use. Meaning, you do not need it if you want to do it "Bronek's way". However you may need to ensure that qemu helper is defined in libvirt configuration - look my messages from past few days.
Second xml is part of VM definition, a sibling to hostdev nodes etc. You can create this part in virt-manager GUI, no need to edit xml by hand - just make sure to select the bridge you have created.
Sorry to pester you with so many questions. I appreciate your help.
Where should the following configuration be placed? What is the config filename and path?
I've done the same. Bridge created with NM and used by the VM. You
Is this placed into your VM XML via virsh?
<address type='pci' domain='0x0000' bus='0x00' slot='0x18' function='0x0'/>
On Mon, Apr 18, 2016 at 5:57 PM, Bronek Kozicki <brok spamcop net> wrote: