I would just like to confirm, but does the idiom 'any time at all' mean 'any time in a day'?-- No, it means any time, completely!
"Don't you be sad" means "Don't feel sad"? -- Yes.
I didn't know the grammar. I think "Don't you be sad(?)" is an interrogative sentence-- No, it is an imperative sentence: Don't (you) be sad. Imperatives can some