I have the vaguest of ideas what it is. As an alternative I could recommend Smoothwall GPL which I know for sure can do VPN (using FreeSWAN), it is also GPL and is some good British software
I think that most of your questions will be answered in IPCops Manual/FAQ/Home Page ; people like to blow their own trumpet about features.
You might find more people with an opinion of it at Linux specific forums, like www.newtolinux.org.uk/forums/ www.linuxnewbie.org www.linuxquestions.org http://voidmain.is-a-geek.net and www.freemypc.com/forums/ and perhaps also you should try www.adslguide.org.uk

Hope they are something to go on.