Yes, you need RpcSs service.
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This service is rather vital. Practically everything depends on this service to be running. This is also one of the few services that you cannot disable via the Services MMC, nor can you change the state with a registry patch.
The RPCSS service is the Service Control Manager for COM and DCOM servers. It performs object activations requests, object exporter resolutions and distributed garbage collection for COM and DCOM servers. If this service is stopped or disabled, programs using COM or DCOM will not function properly. It is strongly recommended that you have the RPCSS service running.
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Source + more info: http://www.blackviper.com/windows-services/remote-procedure-call-rpc/
And: https://technet.microsoft.com/en-us/library/cc787851%28v=ws.10%29.aspx?f=255&MSPPError=-2147217396
For your other questions, you might want to look here: http://www.blackviper.com/service-configurations/black-vipers-windows-7-service-pack-1-service-configurations/
Cheers,
J