I am supposed to 'Explore: Tomb of the Beguiler' and I'm told it's in an area called 'The Crypt' which is supposed to be somewhere in Kroco, but it's not actually labeled on the world map.
Where should I be looking?
You should be looking in the Temple of Storms on the left hand side behind the mander (?name) that stands on the upper level. If you accepted that quest there should be sigils available to you. The Tomb of the Beguiler is an instance level so once you start you need to finish it or restart from the beginning. If I recall correctly it took more than a little bit of time for a friend and I to finish it... perhaps an hour and a half.