Is the importance of the presence of (project management) in the construction companies?

definitely yes

and it is not only for mega and larg project,  it can be implemented for even a very small house/villas project.

اجد من الاهميه ان تكون اداره المشاريع جزء مهم فى الموسسه تدار من فبل فريق متخصص بادره المشاريعوخاصه فى مجال المقاولات وفى الشركات الكبرى تزداد الحاجه اليها

هناك اهميه كبيره لادارة المشروعات فى جميع انواع المؤسسات لان كلما كان التخصص موجود كلما ذادت فاعليته وفى مجال المقاولات يحتاج بالتاكيد الى ادارة مشروعات لتنسيق وتقيم وتفعيل المشروعات بطريقه مدروسه وفعاله....
There are of great importance for the management of projects in all types of institutions because whenever specialization exists whenever higher effectiveness and in the field of contracting certainly needs to manage projects to coordinate and evaluate projects and activating a well thought out and effective manner ..

Yes, Project Management should always be applied whether in low key or full strength.
The criteria to consider is the size of the project.1.
In low budget projects a planning engineer can implement the principles of project management on a low key basis.
It is because the Planning and Project Management go hand in hand.2.
For larger projects a full Project Management team is required to deliver the Project as per schedule and within the cost with quality.

Absolutely, Yes. The project manager is a strategic and tactical value within the company. It is like a orchestra director between all instruments of the project capable to manage and obtain the best of each one to get the success of the project.

As for the placement of the project management, we always need to get project management as an integral part within the team, the problem we usually have with technical teams that they feel seperated, and they are almost always having different view about work, which may not align with the other workgroups.
As you need to get people to buy-in your project, and really work on it, you need to be part of the team, and being from within the operations itself, it would be much better to adhere with.

yes its most important to have a PM..in order to do a project systematically

within construction companies you should have two levels of PM available; local PM site sepcific and a companies own multi-PM.
so the site specific PM should keep track on the risks, delivery dates and resources needed.
the multi project management should takes those into account when planing their capacities (Specially the machines) between the different sites.
the company's multi project management level should for example prevent that two different sites needing the concrete mixer trucks on the same day.
the company M-PM however, cant find this information on its own.
it needs the communication with the engineers and PM on sites to plan the work flow for the resources.
As you see PM is not specified in this example for the construction site itself.
but it actually a net with all other construction sites managed by this company.
the interaction between the different sites should be made by the Multi-project management level within the management level of the company in order to succeed.

Yes, indeed; the PMO is very important in contraction company, must be separated from technical office, I preferred the Project manager has a technical background which it is not necessary but that is my opinion.

طبعا من الاهميه ان يكون لكل تخصص متخصص فى الاداره ده بيساعد اكتر على سرعه ودقه الانجاز وده فى جميع الشركات

Thank you Osama for your valuable question The project management office (PMO) is definitely very important for each construction company to execute projects and deliver their deliverables successfully with in the constrainse of time ,cost and resources.
Without PMO the company will collapse and damages all its investments and will be out of the construction market competence ,because it has no reputation in the sector and has no skillful project manager who can develop a project management plan to lead the company to high level of performance which secures success.
Thank you Best regards