The pressure always has to be corrected in relation to the location of measurement.
The "Noise" you are witnessing can be different depending which hardware you are using.
The sensor has fluctuations, which is normal. However if e.g. the I2C bus layout on the PCB board is poorly designed then you will get additional interference noise.
I'm running 3 different manufactured Arduino platforms, all showing different noise levels. Interestingly my Arduino R3 with protoshield has the least interference noise.