Hinted, unhinted, web, etc. reccomendations

[Cogli]

Given that differents binaries are supplied, are there some sort of reccomendations for their usage? Their names are all quite self-descriptive, but are there really any issues if, for instance, web version is used for dektop publishing? I reckon metrics are different and some POS features are offs, but in what environment or for what script this can cause problems?

As a last doubt, and to appease my curiosity, why out of all webfonts provided by Google, only Roboto comes with this many variant?

Thank you!