What are commonly found characteristics of successful network goods?

This is correct. Since network goods need a sufficiently high user base, too many suppliers simply would not be feasible.

This is correct. If this were not the case, then a user would not have more utility from that good than if more customers were using the good.

This is true. For many consumers the network good will only be attractive if the user base is sufficiently high.

This is true. Switching away from a network good is usually associated with switching costs if all the other users stay with the network good. Just imagine you switch social networks: It is not sure if all your other friends also use this new network which would decrease your utility.