Students need a Cypress, RSL (reserve static line), and a hard-shell helmet until an A-License is achieved. All three become optional after that point (though some dzs here have made Cypres mandatory)
There are no restrictions that I'm aware of from the USPA regarding SOS systems. The ST&A should be consulted on an appropriately sized student rig and canopy for a non-licensed jumper. In the US, every student rig I've encountered uses a BOC (bottom of container) deployment system, though I'm sure there are exceptions.