Answer:
1.) It depends on an individual position and conscience. If I am stuck in such a situation with people of CEO, COO etc stand i'd be worried about not only my job but also about my career. As these kinda instances can dismantle your career and can have a lasting effect.In my case i'd not have volunteered as the CEO,COO have the power to dissappear information and documents. It would be a blind move if i go and volunteer for it and they documents are not found. However, if the situation is different and i am in possession of those copies of cheques then i'd be blunt in sharing the same to concerned authorities. Also if you have the evidence with you ,no position can coerce you into doing anything once you provide it to concerned authorities because then you have the edge.
2.) loans without sufficient collateral, drawing cheques in spouses's names,paying of personal expenses from corporate credits etc.,
These are just allegations ,if none of them are proved in the court or inquiry ,then these are mere allegations. if however,are supported by evidences,these can be a case if unethical practices.
3.) The ethics of a professional Accountant are-
a.) objectivity- Seeing the things as they are with no bias. Assuming everything that you work for as something pure and respect your work in any way possible.
b.) honesty- One who stands honest with his job are poster figures for any department or organisation a person work on or for. It is implied for anyone to be honest to his work.
c.) Professional competence- An employees is supposed to be of professional competence to his work and organisation. He is required to keep.his knowledge update to that level.of oragnisation's requirement.
d.) Confidentiality- is what the Job descripition states. An accountant by profession is not allowed in any way to share the information of his clients or organisation unless law specifies it so.
e.) Professional Behaviour- A professional behaviour. includes reaching the work on time,completion.of duties to the firm , work within the organisation for its betterment etc. It is in the job description in any organisation
4.) FDIC'S OFFICERS should have been more careful and diligent while working on the case. Each and every department concerned to the alleged wrongdoers sould have been checked for evidences which they clearly didnot do. They were not 100% vigilant with their work which is what made the situation awkard for you.
5.) lesson's that can be learnt are- Business are way too practical and decisions have to be made on the merit of the situation. You can follow your gut in business just as you do or can in life. But sometimws all it takes is one moment that gets you in a position where nobody can touch. In this instance if you had those copies of cheques in your possession,no CEO ,or COO can coerce you into doing anything and at that moment it solely depends upon your reading of the situation.
and 
is that the word management means to manage something carefully and good. And the word motivation is to motivate someone to do something weather good or bad.