RE: resources
Hi Hacen
Resources pick up priority (during leveling) from the task they have been assigned to. Double click a task and go to the general tab. There you will see you can set a priority for your task. By default it's set to 500. The range is 0 to 1000 with 1000 being highest. Generally this is left on the default setting of 500 but if you are using Proect's built in leveling tool (Tools > Level resources) you can tell project to take account of the priority you set for each task (change Leveling order to Priority, Standard). If there is any over allocation in your project lower priority tasks will be delayed in preference to the high priority tasks.
Hope this helps - let me know if you have any further questions.
Kind regards,
Andrew