Is it possible to have absolute obedience using Death Note?
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".