If you roll less than or equal to your commander's tactics rating, you must roll on the Naval combat table to see if you successfully avoid battle. i.e. attempting to avoid battle navally is a difficult thing to do so you have to succeed on a 2nd roll. A result of Attrition or Return (or a play of Storms at Sea) means you attempted to avoid battle back to port you sailed from, failed so you must return to the port you are currently in and are forced to fight. So in a 4 player game players always roll on the Naval Table if they succeed in the first roll, whereas in 5 player game only when Carthage plays a card? Also, if the result is Attrition does the retreating force undergo attrition before the battle?
In a 5 player game it would be automatically successful unless Carthage played a card to force you to roll.
Yes, but you must choose a space not containing an ally army if possible. If that is the only space to avoid battle to you move to the space containing the allied army but then continuing moving to adjacent space so you don't end the avoid battle movement stacked with an ally army. Once you enter a friendly space that does not contain an ally army you must stop. Right. I realized that this is the intention when I got to 12.4.1, which lists restrictions of retreat: "addition, a retreating force may not: (...) end the retreat in a space farther from the battle than the closest eligible space."