SAM's PV models read weather files in the TMY2, TMY3, or EPW file format, which are all hourly formats. For now, there is not a way to run the PV models with a sub-hourly time step. We are planning to rework the weather file reader so that it can read subhourly weather data -- that should be available in a future release.
The physical trough model can run with a special SMW weather file that allows shorter timesteps.
As for website notifications, I don't see a setting on the My Account page to only send notifications for responses to forum topics that you post. I'm working with our webmaster to see if we can add such a setting.
Best regards,
Paul.