a) My guest DNS does not transparently work to access my LAN -- only the Internet. The docs @ https://libvirt.org/formatnetwork.html do not provide any guidance for configuring DNS settings. I want to forward requests to the dnsmasq running on the host system.
Oops, looks like this one was easy: a <dns> element as per https://libvirt.org/formatnetwork.html#elementsAddress.