Question: I have a remote win xp machine to which I connect via RDP. When I open a Cisco VPN connection (4.8 client) on that machine, the RDP connection drops because all traffic is routed over the VPN connection now.

Is there a way to make this work?

me => rdp => winXp => vpn => target

Answer: 
Typically the SC is on a 'proper' routable network to allow for management, if you want the SC to deal with the VMs in any way (and it's a **very** bad idea by the way) you need to put the VMs on the same network as the SC or one that is routable from the SC.
Nope, not from the ESX console. Just because these are VMs, doesn't mean you can do batched actions within them from the ESX side of things. You'll probably have to do this the same way you would do it with 32 physical machines - pssh, puppet, etc.

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/edit - missed the fact that there's no network enabled in your VMs yet. Yeah, so @dunxd has a good point - enable DHCP first, then make all your clones, then do your setup management. Just like if you had 32 physical machines.