Some rambling thoughts...

When you are running VPN over the Internet, you have two possible sources for DNS, the ISPs DNS and your own internal corporate DNS server.

Now, in the "Advanced" tab of the TCP/IP properties you may add a number of DNS servers.

If you have two different server addresses and the first responds with an authoratitave NXDOMAIN because the address is invalid, does it use the next server? Or are the additional servers used only as backup in case the primary server does not respond?

Usually, you can only have one DNS server responding, and you need to make a decision whether that is the ISP's DNS server, or your internal DNS server. Either way the other may be inaccessible.

To get around this, your internal DNS server is normally configured to forward lookup requests for domains that it does not manage to an external DNS server.

If your VPN connection software promotes your internal DNS server when you make a connection (and drops it out again afterwards) and you have DNS forwarding configured on the internal server then it should all work fine.

If your internal DNS server doesn't forward requests then it is more problematical.

You don't want your internal name server as the primary when your VPN is inactive as name resolution will try to use it.

WINS is not such a problem, as you are likely to only ever need your own internal WINS server.