Just Op

Developers are allowed to use the Pro as they want. Some may use it to improve frame rate or textures and effects which would benefit 1080p and 4K users alike. Some will just render the game in higher resolution, which downsampled to 1080p translates to a better but costly form of anti aliasing.

Depends on the devs. Most games at a minimum just downsample the games at 1080p

Which has been ruining some games I been told. It is strange that we having that as an issue.

The problem has being blown out of proportion by the FUD campaing orchestrated by Digital Foundry on Pro by doing very cherry picked stress tests videos. And most games having occasionnal framerate drops on Pro have already being patched. 

All games except maybe now 2 games (I believe it's TLOUR 60fps mode and Mantis) have better framerate at 1080p on Pro, something up to 50% higher framerates at some points.

Objectively the Pro is a technical success for a new console with very few problems actually. Don't believe the FUD spreaded by anti-Pro sites like Digital Foundry.

Nioh has a 60 fps mode for the Pro.

Depends on the Devs, but from what I have read and seen I would strongly recommend a 4k television if you want to buy a PS4 Pro for an upgrade, because else, its not much of an upgrade.

If you don't own a Ps4 yet and want the best performance options for the future and/or plan on buying a 4K Television along the road, a Pro is an easy choice.