Question: Nowhere in T'nach do we find this Pasuk in connection with Uriyah, only in connection with Michah?

Answer: The Gemara relies on an incident in Yirmiyah. The Pasuk relates there how, when he prophesied about impending retribution, and the Kohanim and the false prophets converged upon him to kill him, the princes objected. 'Michah too', they argued, foretold about punishment, yet they did not kill him, and so did Uri'ah.

Answer (cont.): This implies that Uriyah issued the same prophesy as Michah, and the only retribution of which Michah spoke is the current one. And that is synonymous with the retribution referred to by Uri'yah!

Question: From where does the Gemara know that the prophesy "Od Yeishvu (Zekenim u'Zekenos bi'Rechovos Yerushalayim ... " refers to Olam ha'Ba, and not to this world, before the redemption?

Answer: This Kashya is answered with the Gemara in Pesach Sheini (Pesachim 68a). The Gemara there states that, in time to come, the Tzadikim will revive the dead, as the Navi (in Zecharyah, 8:4) says "There will come a time when the elders (men and women) will sit in the streets of Yerushalayim, and they will walk "al Mish'antam" (on their sticks), and the same word is used in connection with Elisha ("al Mish'anto"). So the Gemara learns a Gezeirah-Shavah "Mish'enes "Mish'enes" ...

Answer (cont.): ... just as by Elisha, it speaks about Techi'as ha'Meisim, so too, does the Pasuk in Zecharyah speak about Techi'as ha'Meisim. Clearly then, the prophecy of Zecharyah is speaking about the future, seeing as the era of both the first and the second Batei-Mikdash have passed, and Techi'as ha'Meisim has not yet taken place. May Hash-m grant us the Z'chus to see Mashi'ach, Amen!