Using neptune and get my EMAP setup using a general 75psi sensor and i know you have to use the first bar for atmospheric pressure and the remaining 5bar for pressure, but when setting up a basic 0-100 psi sensor for fuel pressure, do you have to do the same?

No. Any fluid pressure would be 0-100 psi .5-4.5 volts generally with most 100psig transducers.

Where are you mounting the fuel pressure sensor

In the fuel rail.

Best to mount off rail if possible, sensors do not like the vibration.

This. I have mine on the fuel rail and I get a bunch of variation in my logs.

Good to know, ill hard mount the transistor on the firewall and use a ling to feed it.

Gauge pressure and atmospheric pressure are not the same. MAP is atmospheric and fluid pressure, 9 times out of 10, is gauge pressure. IE no relation to atmosphere or is compensated upon being energized.