Virtual contexts are not supported as of the current 6.2.3.5 release. We expect support to be introduced in 6.3.
You can run a separate logical device per SSP in the 9300.
QoS is supported.
Cisco doesn't specify conformance (or non-conformance) with RFC 2474 but it does NOT make QoS decisions based on DSCP headers such as are specified in that RFC.