As long as the supplicant can find it, the IP address of the server does not have to be fixed. OpenVPN is definitely the way to go, since it is a user-land program that is not deeply-embedded into the guts of the OS kernel. (All that it needs from the kernel is virtual-device support.) Furthermore, OpenVPN is always "talking to itself." The software on both sides of the link is basically the same.

Thanks, I'd half-forgotten about that -- had it working years ago when I used an old PC then a laptop for a server so could be useful.
Ideally though I'd love to set up VPN so I could have the potential to join friends to the same network and expose other services without opening lots of holes in my router's firewall. Would be easier to connect my Blackberry too as I'm not sure it can use a SOCKS proxy (already have a decent SSH client).
I think I need some what used to be called "remedial classes" in Linux VPNing as it's eluded me so far in the three or four times I've tried to set it up. I was asking about DNS and the like because I seemed to recall that one of the questions asked when creating a certificate was the domain it was for but I think I may have confused it with HTTPS setup in Apache (another thing I managed to do without a hitch).