Regarding links:
Normal Node types have a link limit, so that they may only link to 5 ish nodes. This will stop the whole place spiderwebbing. Or node links can only be a certain length, so you cannot link to a node miles away, you have to go through other nodes.
This will make the need for sign post and map nodes.
these could be incorporated into all hubnodes as images, the trick would be generating them automatically