There are a few questions in here so let me try to address them individually.
It sounds like you’re trying to create one record per project, but also generate an output where all the project for a specific owner are placed together. This can be done fairly easily - you can greate boundaries per project in your data mapping configuration, generate your 2-page-per-record output in the Designer module, and then using the Job and Output Presets, sort per project owner, and split between them. One PDF can thus contain all the projects for one owner.
The only thing that’s slightly more difficult, is the “Number of unique project owners”. In DataMapper and Designer, you cannot have access to any records before or after the current one, neither can you “count” the number of records.
However, this can be done through Workflow. It would require a little bit of work with Metadata, using the Level Creation and Field Management tasks, but definitely could be done, especially if you want some sort of report page.
This is unfortunately not “trivial” and requires a certain understanding of metadata. I do have a few how-tos that may help put you on the right track though: