Moca mora mea
Hi
MEA ensures you both reception of navaid throughout the airway and obstacle clearance 1000ft or 2000ft if over high terrain - above 5001ft -
MOCA ensures you obstacle clearance throughout the route but reception only when within 22nm from the navaid defining the route.
MORA is a jeppesen derived altitude that ensures you obstacle clearance when within the square. Why MORA? Ask yourself how often are you flying from vor to vor?
Hope it helps.
PS if i were in your shoes i would follow the hints from the previous posters: read the Jeppesen intro - there is a wealth of information in those pages!!