ADM1270 Issue

hi sir

I  want to design the ADM1270 in my system, but I have two issue need to clarity before layout

Q1.ADM1270 use the PMOS to be the switch, but PMOS cost Which expensive than NMOS, Why ADI use PMOS?

Q2.ADM1270 Have reverse protect by RPFG,But I can't find the RPFG vary which no matter passive voltage or negative voltage input

     can you help to clarity?

thanks