You should turn down your brother's request as divulging to him the interview questions will not only jeopardize the fairness of the recruitment exercise and betray the interest of your company, but may also breach the company's policy. You should report your conflict of interest situation, i.e., your brother is an applicant of the recruitment, to your company for its consideration on how to handle it.

Although you are on good terms with your line manager, you should be decisive in reporting the case to your company as it involves serious conflict of interest or even illegal activities, e.g. fraud or deception. By turning a blind eye, you will fail to protect the interest of your company and other involved stakeholders. You may even be suspected as a party to the crime.

It is an offence under Section 9(3) of the Prevention of Bribery Ordinance by submitting false documents, e.g., inflated travel allowance applications, to deceive the employer. "Norms" among colleagues cannot be a valid excuse. You should say "NO" to taking part in any illegal activities.

Rebate is a kind of advantage. If you offer an advantage to an agent, i.e., the procurement manager in this case, as a reward to him for closing the deal, you may be liable for an offence under S.9 of the Prevention of Bribery Ordinance. In any case, don't run the risk of committing a bribery offence as it will ruin your career!

You may commit a corruption offence under S.9 of the Prevention of Bribery Ordinance by accepting an advantage, i.e., loan of money in this case, for turning a blind eye to the misconduct of your colleague in his work. To stay away from corruption, one should avoid running into financial difficulties and stick to the highest standard of integrity at all times.