As far as your first question is concerned, Uriel V ascended to the throne immediately after the ravages of the Camoran Usurper. In many respects, the invasion of Akavir was supposed to be a publicity stunt to remind people that the Empire was still strong and glorious. No doubt it was also supposed to raise his own stock with the people and the nobles, both from the glory that reflected on the Empire and those within it, but also the riches that he no doubt hoped to drag home to Tamriel as booty and disperse to his greatest friends. It is interesting that Uriel's death actually cemented his own personal reputation for greatness, regardless of how it reflected on the Empire as a whole, because it made him a near-mythical martyr-like figure, despite the failure of his enterprise.
I believe a real-life comparison would not be out of order here, although I'm not sure how the rest of the forum will appreciate it. I personally believe that the emperor who invaded a foreign land and was made glorious for it was named "Uriel V" as a direct reference to Henry V, the English king who fought at Agincourt. Henry basically rebooted the Hundred Years' War against France, and Agincourt was a huge morale booster for the English; he also died relatively young, though not in battle. The Hundred Years' War actually turned against the English not long after Henry's reign, however, making the success of Henry's battle rather pointless in the long run. I really think that Uriel V was modeled in large part on Henry and this war, so any lessons we take from the Hundred Years' War might be considered relevant when discussing the Akaviri invasion as well.