Hello and welcome to just answer,
The primary 02 sensors will be between the exhaust manifold and the catalytic converters, These monitor engine fuel ratio and the secondary ones monitor the converters.
The drivers side is where cylinder #1 is and it is labled bank 1, the passenger side is labled bank 2, the primary sensor is labeled sensor 1, the secondary is labled sensor 2.
1/1 primary drivers side
2/1 primary pass side
1/2 secondary drivers side
2/2 secondary pass side.
Sorry for the delay,
Yes this could cause problems any time you "tap" into a factory harness especially a sensor signal, the 02 operate on millivolts if you create resistance when connecting this will skew the signal sent to the ECM.
If you are set on connecting the gage, I would recomend soldering it in for the best possible connection.
As far as the narrow or wide band, I am not positive on this but I am about 95% sure it is the narrow band.