White smoke, burning coolant. Black smoke, burning oil. A general rule of thumb, but it could be burning both.
Intake gaskets are extremely, extremely common on any small-block Vortec. It could be a head gasket, but I'd bet you it's the intake. They all fail on these engines it seems.
I'm planning on doing mine in the spring, as a preventative measure. Not bad yet to my knowledge, but I don't know if they've been replaced or not.
Burning a little oil is pretty common in my experience, I wouldn't worry too much about that unless it's really excessive. Going through coolant though, is not a good sign.