It would be more useful then the current state of affairs. With a proprietary blob to talk to, it would be possible for people to do things like write text-based clients in curses, or the suggested 'server' version of Skype specifically for running as a super node or relay node.
We don't know how flexible the blob they give us will be. Since the current interface has no provision for toggling or dealing with one's status on the P2P network, there's no reason to believe that that will necessarily be a feature that the blob exports; Skype may still keep the network communications totally opaque, all handled behind the black magic of the blob, which would simply export the basics like contact list, etc.
Not necessarily. We already know that things like supernodes are selected based on network conditions. The 'server' interface could just be a reduction of dependencies so that you could run it as a daemon process on a server. The Skype Network would then select it as a super node so long as the server had the right conditions (no NAT, no firewall, fat pipe, etc)
It presumably would still need a Skype login, but that could also be used to control it. Accepting commands from a white-list of Skype Ids.
