1. The purpose of a report is to persuade your readers with a stance.

Correct

Incorrect.
The purpose of a report is to communicate new findings, analyze business matters and suggest possible improvements or fixes to an issue. We usually persuade with a stance in academic essays.

2. We use headings and sub-headings to highlight the content of a particular section.

Correct

Incorrect.
We should use headings and sub-headings to highlight the content of a particular section.

3. We should not use linking devices in a report.

Correct

Incorrect.
Linking devices like conjunctions, headings and topic sentences are necessary in a report as they help to show linkage among different ideas.

4. A report includes an introduction, findings and a conclusion only.

Correct

incorrect.
You should also include a section of recommendation as you may want to provide some suggestions based on your observation and findings.

5. Long texts are much preferred when writing a report.

Correct

Incorrect.
You should notice that your superiors may be too busy to read long reports. Do keep your report brief and succinct.