Hi,
1. I get the modeling of underground (UG) span with the Conduit feature class and conduit geometric network, but I don't see how to model aerial span.
You should also see a "Fiber - Overhead" sub type on the cable. Assuming you are using ArcGIS 10 you should be able to just click the "overhead" template item and that will created a cable designated as overhead.
2. I need some guidance, also, on modeling the transition point on a fiber cable between aerial and underground. Will I need to model those points as end points of an aerial cable and an UG cable joined by what...? A FiberInterconnect feature? Can I splice, then, inside the FiberInterconnect with pass-thru splices? Or do I need to place a SpliceClosure feature at the end points and make pass-thru splices?
Yes, given our fairly simple model at this time, you would need to model the transition as a splice closure location with pass through connectivity. You could also place equipment there as the transition (without a splice closure) if that is actually what you want but i suspect there would not be any in most cases. For now the splice closure with pass through is the way to go.
Hope that answers the questions.
Regards,
mark