OpenVPN + 2 Routers on one Pipe?

I work a lot from home these days and would like to setup two routers for one Internet connection. I'm new to all this so I would really appreciate some feedback to my planned setup.

I have the router from my ISP (ISP router) which is some no name router and plan on getting a modern router that supports DD WRT to run Open Vpn (Vpn router).

I would like to have the Vpn router connecting to my vpn via Open Vpn and the other router to just access the Internet like always.

1. How can I set this up? Do I connect the Vpn router to the ISP router?

2. What modern, fast router that supports DD WRT can you recommend?
http://www.dd-wrt.com/wiki/index.php/Supported_Devices

Any help would be fantastic!