So im looking to setup a system in a very remote location where it is impossible to get a connection to the outside world (3g maybe!)
anyhow what I want to know is will the system still operate without an "external" router?
Oh and will I be missing stuff like updates etc even if I take the final release of 810?
You could install the core with an internet connection. When everything works (also install the MD's up front), move it to your igloo.
You will of course not have the services available that use internet.