Unbalanced to balanced audio signal conversion
You are correct about the feedback connections.  The inverting and non-inverting inputs of both amps are reversed.  Also, there is no reason for a full differential amplifier topology because the input is not balanced, so there is no "differential" other that the single-phase input and its GND.

For this most basic approach, start with two completely independent opamp circuits, one inverting and one non-inverting, both with the same gain magnitude.  Note that the impedance of the inverting amp's feedback network directly sets that amp's input impedance, so keep it at around 10K or above.

A shortcoming of this approach is that if one side of the balanced output is disturbed, such as shorted to GND, the other side continues to make its full amplitude output.  For a more complex balanced driver, look at app notes from THAT Corporation and Analog Devices.  Both make chips for this function, and their internal schematics and explanations should be helpful.

http://www.analog.com/media/en/technical-documentation/data-sheets/SSM2142.pdf