Is it possible to insert some image (logo) into one Powerpoint slide and have it exactly in the same place on other slides? Do I need to edit some kind of layout? What if I need that image only on specific pages having similar layout?
Yes, it is possible using the Slide Masters. You can use slide masters to make global changes on all the slides in your presentation. Here is a tutorial about slide masters which also explains how to add images.
You need to create a new template.
Create your layout for a page, including logo and then select File > Save As... and select "PowerPoint Template" as the file type.
If you require more than one layout that can be done to. Investigate the layouts that come with the default template. There are several different layouts:
There's a demo/tutorial in the online help.