Can an isolation amplifier be used to block common mode noises and capacitive coupling?
Yes, but they are not cheap. Try looking up AD202 and the AD210 analog isolators from Analog Devices. The source could be Digi-key or Mouser. Both are available as a 1" wide x 2" long module, or a vertical 2" long by 1/2" wide package.

They have an isolated 15 volt power pin and ground, which powers both the input and output sides.

You have 1,500 VAC isolation from the supply and inputs/outputs.

For creapage isolation you can slot-cut the PC board just inside the input pins, which also supply +/- 7 volts to power an op-amp if needed.