Dealing with Death at the Workplace

BLUF: How do I react to an unexpected death of a colleague in the below situations:

1. The employee is one of many of my directs

2. The employee is a key member of the team I am coordinating (non-projectized org.)

3. The employee is a peer of mine

Unfortunately, over the weekend an collegue of mine passed away unexpectedly. Certainly, my first thoughts are with the family and friends of the deceased person. To be clear, I do not want to sound insincere or selfish in this time of sadness.

After a few hours of sadness, I saw his manager and the gears began to turn. What does his manager do? How does he cover today's work? Who can/should go to the proceedings? How will this employee's departure effect me? What should I do? Should I attend the services? Send flowers? Speak with his closer friends? How soon is too soon to discuss the gap on my project team? What about deliverable "X" that the person owned?

Thankfully, I am at the earlier side of my career and have not yet had to deal with this crisis situation. It seems like there are no right answers. I'd love to get perspective on the situation should it ever happen to me.

Thanks in advance for all the replies!