I have about 400 non-domain joined machines. They're not part of our physical network and don't have VPN access.
I am going to assume I need to have these folks manually install the software locally. Is this correct?
How does Lansweeper "report" back to the server? Do I need Domain access or does this respond back without using a domain ID and password? Since these don't have a physical connection to our network, do I need to make sure all of these machines VPN in if my Lansweeper server does not live in the DMZ?
If there are no TCP/IP or VPN connections between your various sites, then each site will need its own Lansweeper installation consisting of a database, service and website. Each installation will be self-contained.
If there are TCP/IP or VPN connections between your sites, you can (with the Enterprise license) add additional scanning servers at each site, which will report back to your central database.