I will go by what is on
the AEPhi website.
The letters are derived from "Aei Esto Philio" = "May Friendship be Everlasting". There is another secret meaning, revealed at initiation.
The meaning of our colors is public.
The Columns (I guess it's technically not a crest
) has some symbolism that is explained to new members, and further symbolism revealed at initiation. I -think- that what is told to new members is public (I seem to recall seeing it on a chapter's website), but I'm not sure, so I'll err on the side of caution here.
The new member pin is a replica of the Columns without the Greek letters - so the new members know some of its symbolism.
As for everything else, mum's the word