Umm... could someone tell me when you use the Naval Combat Table?
The Naval combat table is used when attempting to sail to a Carthaginian controlled port or on all Greek naval movement if Carthage allies with Rome. (9.6.4).
Also, with regards to Agathocles Lands in Africa, is this considered Naval movement?
Agathocoles Lands in Africa is NOT considered a naval movement which is why the event text says Place him instead of Move him.
If the Carthaginian Citizen Militia as been moved to Carthago, and the Greeks land with no battle taking place, is it a Greek Controlled Port or a Normal Port? (I think this has some relation to the placement of Enemy PC)
This was clarified in version 1.2 of the rules. As long as Greek CU are in Kerkouane it is considered a normal port, ie the Greeks can sail there. Once all Greek CU are removed from Africa they can no longer sail to Africa. ie you get one chance to take Carthage.