Originally posted by luponix:

1. is not true. your first and second portal are not bound to connect. the tag is empty so every portal that you place with an empty tag will look for another unoccupied portal with the same tag. so if someone else already placed such a portal your first one will connect to that one and your second one will stay unconnected (its global, not by player)

good stuff. especially the exploration portal is usually such a time saver

the very first portals (if unnamed) are connecting to each other