What advantage does the second shield generator of the FORCE provide? Will it provide life support (atmospheric shielding keeping oxygen in/non-breathable atmosphere out) to the pilot?

The shield generators on the X1 Force are defensive in nature and aren't a Tevarin-style "air shield" you might find on larger spacecraft. All of the X1 Variants and current spacebikes from Drake and Aopoa are "open-canopy" craft and therefore lack integrated life support. You're going to want to wear an appropriate suit for the environment you expect to be riding through.