sub material type under material type and sub material group under group

1. Is it possible to define few sub-material type under material type and same some sub-group under main material group.

For example:

For material type spare, we want to define sub material type imported spares, domestic spares.

For material group Electrical, sub group Light & fittings, AC & DC drives etc

2. Can we associate more then one Material Type and Material group for single material?

thanks