The Free Software Product model has 100% of the software covered by an open source license, but distributes the software as a complete, supported product under a proprietary license.
Free Software Product companies use their trademark rights, along with the license of the software itself, to create proprietary derivatives. If there is a 100% open source distribution, it uses different trademarks and naming conventions, and receives little or no direct support for users from the upstream.
A cornerstone of this model is that the company produces little or no proprietary software. It allows the community to collaborate and makes it harder for proprietary derivatives to thrive.
When a single company provides the bulk of the effort to create and sustain the project, and has a clear target market for the product (typically the large enterprise).
Any kind of monetization is possible on the product. Because it is being distributed under proprietary terms, the options for monetization are unlimited. For those who might wish to create downstream versions of the project, they too are free to monetize as they see fit.
Yes. By keeping 100% of the software open source, and not producing any proprietary features, the community is free to collaborate with the upstream. A 100% free downstream distribution can be created, and distributed - optionally with complete monetization.