Is it possible to create users and autorization profile per users ?
Of course.

Otherwise it would not be really Collaborative
Is each user able to enter in the tools, to see only his own task, and to enter his own imputation per task for the week ?
Yes for team members.

Project Members can have larger view (all tasks of their projects).
But the greatest is that all access rights are configurable throught profiles. You can define your own prifiles, define with view on each item. ProjeQtOr is very flexible.
If yes, is there a validation workflow ?
Yes, defined throught acces rights.
Project memebers submit weekly real work input.
Default configuration allows Project leader to validate (or reject) this work input.
Is the application fully compatible with EasyPHP DevServer 14.1 VC9 ?
After installation, when loggin when admin/admin, nothing appears.
After closing windows, when try again, admin/admin is a bad login/password.
It should, but I did not try exactly this version.
Did you have correct configuration ?
Is the database full with table or not ?
Can you check log file for reported errors ?