skowal

You should give each location it's own network, this way you can use a routing protocol (or default gateway) to send Internet traffic out through a non-VPN route. Of course, this means that each site would need a router.

For DNS, you can have a DNS server on your DC and point all of your workstations to that DNS (DC) server. Remember that your Windows clients need to access your AD's DNS in order to find the DC. In your DC's DNS config, you can forward any Internet DNS requests to be resolved by the ISP of the site for your DC. A disadantage would be that if your intersite VPN links went down then you would not be able to resolve Internet names.