Where/how is permission obtained when required, and under what important circumstances can a stay be extended or changed?
For residents of India, the visa is requested at the Italian Consulates General in Bangalore, Kolkata or Mumbai, or the Embassy in New Delhi. After entry for business, no residence permit is requested, but presence must be declared: by the Schengen entry stamp at the border when arriving from a non-Schengen country, or at the Questura within eight days when arriving from a Schengen country (a hotel declaration also counts). The official source does not state when a stay can be extended or changed.
See recorded sources
Limits of the record- Extension or change of a stay is not described in the captured sources.