Is it possible to have absolute obedience using Death Note? We've seen Light completely manipulating the robber in the bus-accident case (in which he figured out the identity of the FBI stalker). At the end, though the robber died, but everything went according to the book or in other words the robber was completely manipulated. 

So my question is, is it possible for Light to gain absolute obedience over the victim without killing him? If so, why doesn't he utilizes this power? 

One possible way to gain absolute obedience is to write a task for the person and make the person's death to occur after a long period (say fifty years)
There are a few practical limits.

In the movie the death had to occur within 23 days.

In the anime, Light experimented with what he could make the victims do. If it was physically impossible for them to do something, nothing would happen.

Also, remember one of the rules:


  After writing the cause of death, details of the death should be written in the next 6 minutes and 40 seconds. 


That's not a whole lot of time to write down what someone should do. 

Apart from that, the victim would be forced to do what was written, as Light discovered when he did his experiments.

Also, it only seems to affect the target of the death. It was pointed out somewhere early in the anime that others could not be coerced. When Light tried to find Ray Penbar out, he had to create a pretty complicated scenario. He could not just write "Any FBI agent will now reveal him- or herself".