:::::: Heat as a noun meaning the energy transferred during the process of heating is fine with me. In the stream analogy then, heat (noun) is the amount of water added by the stream named "heating" (verb). Work (noun) is the amount of water added by the stream named "work" (verb). I'm just trying to cut through the thrashing around.  

 :::::: Work is what is directly measurable through non-thermodynamic means (e.g. mechanical dW=fdx). The remainder is heat, assuming no transfer of energy by mass transfer.  In the stream analogy, you measure the water added by the work stream (~the work), measure the change in the amount of water in the pond (~the internal energy), and the difference is the amount of water added by the heating stream (~the heat). Applying this to the friction scenario, I would say yes, if you break the system down into subsystems, they must be described by both heat and work processes, in contrast to the simple compression of a non-viscous gas. If you don't break the system down, then dU=dW, end of story.