Progess section: start date; end date and duration

Duration is always an integer, in days (it represent open days).
It is just the difference between end and start dates.
As ProjeQtOr does not manage hours in the day, you cannot define duration less than 1 day or not interger.

But this should not have impact on planning if you run work driven plannng (as expected on projeqtor).

You may find information searching "effort driven" planning (it is how MS-Projects calls it), or "capacity" planning.

To set is short, you may have "duration driven" or "effort driven" :

• in duration driven you fix the duration : then adding resources adds work
  For instance, I must execute a task in one month. If I assign 1 resource, it costs 20 days.If I assign 2 resources, it costs 40 days. Duration is fixed (20 days)
• in effort driven you fix the work required to execute the tasks ; then adding resources will determine duration
  For instance, I must execute e task estimated at 40 work days. If I assign 1 resource, it will take 2 months, if I assigne 2 resource, it will take 1 month.

Only effort driven really gives capacity planning, because you give the real estimated workload to execute the task.
In duration driven, you don"t estimate the required effort (work) and you let your delays drive your planning : if you don't follow up very frequently every task, your will be always late because you won't see it assigned resources are enough to execute the task in given duration.