Co-Worker is leaving soon and how do I ask him about some things regarding the company? Is it a good idea and how should I ask?

Just politely ask

Would you expect a straight answer? I wouldn’t.

Asking about this subject is potentially very tricky. You can certainly talk to the person who is leaving, but I would resist asking direct questions. I would keep it simple. Ask them if they have any advice on fitting in to the company.

Do you know why they are leaving? I think it may be important. If they are disgruntled, I would not ask them anything. If it’s because they got a better job, then you can ask all you want. In any case, you have to realize this person may have reasons not to be completely honest with you.

Do what your gut instinct tells you, exactly that.

This is best done off-site where this person will feel more comfortable being candid. I would invite them out to coffee. Listen and watch body language. Contribute nothing but general sympathy to their plight, not necessarily their opinions. You don’t know if this will boomerang via others this person knows in your company of whom they may later talk to—and you may need plausible deniability if a superior is stupid and paranoid enough to question your loyalties. Ethically, I see nothing wrong with this and you might even broaden your network in the process. It’s always good to know people in your industry whom you’ve once worked with. It’s also invaluable to have info concerning your company’s future or mismanagement.

Why on earth are you waiting til now? You should ask ALL concerned about being excluded from anything you feel would benefit you in the performance of your job, and you should voice such concerns in EXACTLY that fashion. The issue is just that vital.

Throw some humor his/her way. As they are leaving, politely ask “What should I do if the shit hits the fan??”

Why do you want to ask these things to your co-worker? You should take up them with your boss in a polite manner by raising your concern.

As Corvus said, i would do this off site to improve the chances of an honest reply. Invite the person for lunch.