1. When is the due date of the report?

It is on May 1st.

2. When is the deadline of the book?
It is tomorrow.

3. When is the report due?
It is due this morning.

4. When is the book due?
It is due this Thursday.

(Are the questions and answers all correct? Are the questions the same? Do we have some other expressions?)

They're all correct.

The questions and answers you provided are correct. They all ask about the due date or deadline for a task (report or book) and provide specific dates or timeframes as the answers. The questions are similar in that they all inquire about the due date of a task but use different phrasings and wordings. Other expressions that can be used to ask about due dates or deadlines could include:

- What is the submission date for the report?
- When is the book expected to be finished?
- By when should the report be completed?
- What is the cutoff date for submitting the book?

These are just a few examples, but the key is to ask a question that clearly indicates you are seeking information about when a task needs to be completed.