Overlapping hours do not count. Yes, you do consider all the projects, but again, the overlapping will not be counted. If I remember correctly, when the experience is applied for, the PMI website will truncate your time accordingly.
The hours have to be based on leading and directing a project according the PMP exam content outline. See the PMI PMP handbook.
You need to focus on the project, not the product. A product is usually the result of a project or operation, so make sure it is actually a project by the PMI definition.