re: Pomegranates
The actual statement of the Gemara is that “????? ??? ????? ????? ?????,” which means, “The empty ones among you (K’lal Yisrael) are full of Mitzvos like a pomegranate [is full of seeds].”
I always thought the clear implication is that a pomegranate, while full of seeds, falls short of 613.
re: Mordechai and Esther
I love The Purim (urim) Story (ory), but even they were a bit confused on this point. When Esther is about to be abducted by Sir Toe-Face, she calls to “Cousin Mordechai!” Only a few minutes later, in the song, she addresses, “Uncle Mordechai.” Later, when debating whether to go to Achashveirosh, she again sings to “Uncle of mine.”
There is no source for the idea that Mordechai was Esther’s uncle (which would actually not preclude him from being her cousin as well).