Shoukaku's poem at the end is the first half of a poem titled "When I Sortie" by Ogata Jou, a 23 year old kamikaze pilot. He sent this poem as a farewell letter to his mother. The poem is written in old Japanese so it's hard to translate it while keeping its meaning in English. As it is in all literature this is just my interpretation of the poem in English and is by no means definitive.
To a more lighter topic, people may be wondering what is going on with Zuikaku and Enterprise's T-shirts. This is actually based on a Japanese meme from a line in Yu-Gi-Oh GX by Kaibaman. 強靭 (Tough) 無敵 (Invincible) 最強 (Strongest) 粉砕 (Pulverise) 玉砕 (Honourable defeat/death) 大喝采 (Big Applause). So far we've seen all of them except "Big Applause". If you're curious I found a 25 second clip with the lines on https://www.youtube.com/watch?v=rF4MnKQxTWo. I also tried finding it in English but they cut the scene for the English dub so yeah...