IIRC they said the fuel will be a new commodity that can be purchased from certain stations or mined in the wild.
I would assume it will have a Shipyard function - otherwise i fail to see how you could transport your ships to your FC - but it may work only for the owner. The guests won't have access to it.
Regarding the capacity - i would assume it will work the same as an outpost or megaship - pad hogging can be an issue while multiple instances will overcome that.
Now about the POI - i assume the FC POI will be visible only to the ones that have permission. Pretty much like wingmate beacons.
This way you can have 2000 FC in SD, but one will see only the FC that allows him to dock.
It will be interesting to see how permissions are dealt with: individual names (probably limited to a number of entries).
If they do add Squadron permission, this might prove to be a problem for large squadrons if the said squadron decide to converge all their carriers in the same system (stupid yes, i'll admit that)
Regarding the interface - i assume it will be something megaship/outpost like. Basic functions like repair/refuel/rearm will be available to all FC (and shipyard for owner only)
Then comes the support modules, each adding one or maybe more Services:
Exploration will add Universal Cartographics and maybe some outfitting options
Trade/Mining - will add commodity market (average galactic prices - is a possibility) and aslo maybe some outfitting options
And so on for each role.
The thing that annoys me is the possibility that the carrier will be limited in the number of support modules it can fit. I do hope they will allow multiple support modules.