1. R' Tzadok Risisei Lyla p. 139 - Megillas Esther begins and ends with a vav - the vav ha'chibbur. The Likutei Halachos concerning the six levushim that Mordechai wore in Esther 8:15 says there are six bechinos in Torah (kasher/pasul, tamei/tahor, assur/muttar).
2. Based on the Divrei Shmuel of Slonim - Mordechai is ben Shim'i - ozen shoma'as. See also Esther 9:4 - "V'shom'o [Mordechai's] holech bechol ha'Medinos."
3. Chatzi ha'Malchus: Malchus in gimatriya is 496 - half of that is 248 - Ramac"h - if the mitzvos penetrate all of one's 248 limbs, mida k'neged mida Hashem responds (Hashem tzilcha - the Besht - your reflection) and Malchus is complete.
4. The Divrei Yechezkel contrasts Esther 7:2-3 with 6:5 - two leshonos of bakosho vs. four - the first is bechinas Y-H, before the yeshu'ah (ein ha'shem shalem), the latter bechinas Y-H-V-H, shem shalem. It would seem, then, that Tov corresponds to the Yud, chen to the first Heh, Kasher to the Vav, and Tovah to the second Heh. V'duk in 9:13.
5. A fascinating insight from the sefer Pri ho'eitz on why shem Hashem is not in the Megillah: Were there to be shem Hasem b'feirush, there would be a backhanded zechus to Amalek having served as the vehicle for Kiddush Shem Shomayim. The Megillah emphasizes that any such conclusion is incidental, and no zechus accrues to Haman.