Was it random drafting or was it a personal decision? What were the benefits to family etc for signing up?
The idea of sending pilots on one-way suicide missions is largely attributed to a Capt. Motoharu Okamura. He is quoted as saying:
In our present situation I firmly believe that the only way to swing the war in our favour is to resort to crash-dive attacks with our planes. There is no other way. There will be more than enough volunteers for this chance to save our country, and I would like to command such an operation. Provide me with 300 planes and I will turn the tide of war. World War II: the Encyclopedia of the War Years, 1941-1945 - Norman Polmar & Thomas B. Allen p463
It must be remembered that the idea of death before defeat was firmly ingrained in the Japanese military culture of the time.
This provided the catalyst that led to for Vice-Admiral Takijiro Onishi creating the first Kamikaze squadron. All 23 pilots in that squadron were volunteers.
From that point, although it has been claimed that there were more volunteers than there were available planes, interviews with surviving pilots suggest that young pilots were actually forced to fly the suicide missions. Japanese fighter ace, Saburo Sakai, was one experience pilot who claimed that he was forced to fly a kamikaze mission, but failed to locate his target.
The rewards for being a kamikaze pilot? Simply the honour of dying for the Emperor. But we should never underestimate just how ingrained and prevalent were the concepts of honour and dishonour in Japanese society at that time.
This is an excellent article by James Burbeck on the Kamikaze phenomenon in World War 2
It seems to have been very simple: Classes of newly graduating pilots were asked to volunteer, and the entire class would volunteer enthusiastically by doing so with both hands. The attitude of Japanese society can be judged from the fact that, even fifty years after the war, kamikaze pilots who simply failed to find a target were still being shunned.
Some veteran pilots were allowed to demur, as with Tetsuzō Iwamoto who stated his belief that fighter pilots should be tasked with shooting down enemy fighters and was allowed to train Kamikaze pilots instead.
This may all sound flippant, but that is not my intent. There seems to have been no need for any explicit coercion, because the implicit coercion, from peers and society, was far more than sufficient. There was no greater dishonour than to refuse a request from the emperor's appointed representatives to die for Japan.