Determining Bandwidth of any circuit
And on what factor should the cutoff of my LPF depend since the sensor
  is just giving DC differential output.


Your application is a very sensitive Wheatstone bridge and, if the signal you are looking for is basically DC, then you want your filter cut-off frequency to be as low as possible in order to reduce noise from the op-amp amplifier. But, in reality you can't have a LPF with a DC cut-off frequency because nothing will ever change and, the component sizes will be infinite so you have to re-examine your requirements and possibly 10 Hz might be a good filter cut-off.

You are sampling at 19.2kHz but that is now irrelevant to your design - you could sample at 100Hz and get the same performance if 10 Hz is your low-pass filter. Remember, the LPF does two things: -


Gets rid of unwanted self-generated noise from your op-amp amplifier (this is your main problem)
Prevents aliasing (this won't be a problem because nothing will get through a 10 Hz filter that would cause aliasing when you sample at 19.2kHz)


In your previous question I reckoned your op-amp had a noise of 60 nV / \$\sqrt{Hz}\$ but, if you restrict your bandwidth to 10Hz, the sum of all the noises will be over a bandwidth that is 16Hz (believe it or do the math! link) therefore, your equivalent noise at the input to your op-amp will be \$\sqrt{16}\$ x 60nV = 240nV. This is then multiplied by your op-amp gain (say 10) to give you a real figure of 1.2 micro volts into the ADC.

In your previous question it was 10 micro volts because I had assumed the BW to be 16kHz.

Remember also that the op-amp noise will rise (per Hz) as frequency falls and that in the DC to 10Hz range there will be another figure in the data sheet for the op-amp that covers this area. I'm not sure about the MCP6v07 and how well it's "auto-zero" feature works well at eradicating this LF noise so you'll need to check. However, if I looked at the ADA4528 (because I use it similarly to you) it has only 97nVp-p noise in the 0.1Hz to 10Hz bandwidth and this is a really good figure for an op-amp, made so by the auto-zero feature. It appears that the MCP6v07 is 1.7 micro volts p-p for comparison.

Is this good-enough? - I can't tell you because I don't know what gain the op-amp is needed to be set at and I don't know your requirements - I can only make comparisons.



Noise Equivalent Bandwidth - for a low pass filter the NEB depends on the order of the filter: -

Noise bandwidth = 3dB cut-off frequency \$\times \dfrac{\frac{\pi}{2n}}{Sin(\frac{\pi}{2n})}\$ where n is the order of the filter. For n = 1 this reduces to Fc x pi/2