Each of our tasks have a number of hours that the employee has to respect.  But most of the tasks needs more days than what the system calculates.  Is there a way to override the dates?

Let's say our project manager sends a design to be approved by the client.  We create a task for 15 minutes but we give 3 days for the client to get back to us so the task should be 3 days with a duration of 15 minutes.

Another scenario is if I have a task of 40 hours for a programmer and I want to give her/him more than 5 days to complete it because we might need her/him on support that we can't really plan.

In a project template, you can specify dates and duration.  That is perfect.  But when the project is started, if you move a task, the days are not respected.

Can you help?  I think this is basic project management and it's probably me that is missing something.  Our old open source system (Web2Project) could do it.

Thanks.