1. When creating an edge as part of the creation of a vDC if you don't tick the box to configure IP settings for the edge (assuming you will do it later) AND the first external IP range (sorts by numerical order) is exhausted the edge will fail to create along with any organizational network you also specified to create. It appears that by default the edge will try to assign an external IP from the first IP subnet in the list, if this IP range has been exhausted edge creation will fail. To get around this you can tick the box to configure IP settings when creating the edge you then can then untick the "participate" box next to the exhausted IP range. This then allows the edge to pick on IP from you non-exhausted IP range and creates succesfully and the edge all works OK.
2. Even if you use the workround above there is a bug in that when you right click the edge and select "External IP Allocations" it shows as blank even though the edge is functioning OK. You can view the assigned external IP by going into the properties of the edge and clciking on the IP settings tab.
The above appear to be bugs, anyone know how to log these with VMware as bugs ?
Can you make sure you're on vCloud Network and Security 5.1.2a specifically? I'm assuming the issue will repeat with the updated version given that the process is mostly vCloud Director based.
The IP assignment from the External network is based on LRU (least recently used), and should be the same engine that assigns IPs to NICs of virtual machines (afaik).
For note 2, if vCloud Director's website is blank ... can you create a test VM that is directly connected to the external network and see if it will accept the same ip address assigned? you don't have to power it on, just set the IP mode to Static Manual and see if you could theoretically create a duplicate IP scenario.
If so, then this process is not setting the IP to be allocated to the Edge. Sounds like a bug either way, but it may be directly depending on the first issue.
For issue 1, can you file a support request and provide a detailed set of requirements and screen captures to reproduce?