Which aspects have a direct influence on the utility a consumer derives from a network good…

That’s exactly right according to the theory of network goods. The stronger the network effect, the more utility is derived.

That’s exactly right according to the theory of network goods. The network good has to be valuable for potential customers.

That’s exactly right according to the theory of network goods. For many consumers the network good will only be attractive if the user base is sufficiently high. Think about the telephone: If nobody has one, the utility of having one is zero because the only user cannot call anybody.