The Question and Answer section for The Metamorphosis is a great resource to ask questions, find answers, and discuss the novel.
Kafka was known as "the writer who didn't want to be read". There is only speculation as to why he ordered Brod to destroy his work. Perhaps his sickness, tuberculosis, and his intense melancholy contributed to his desire.
From the text:
He was standing up straight enough now; dressed in a smart blue uniform with gold buttons, the sort worn by the employees at the banking institute; above the high, stiff collar of the coat his strong double-chin emerged; under the...
Gregor is unable to eat anything fresh, but he is able to eat the moldy cheese and vegetables.