All of the Pseudojuloides species I have kept have been pretty hardy once they have made it past 2 weeks from being shipped. The ones I have had, both severnsi and cerasinus, have not been picky regarding foods and have been extremely peaceful.
If you have established wrasses in your tank there may be some aggresion towards the pencil wrasse, but nothing too bad, at least with fairys, flashers, and Halichoeres wrasses, Pseudocheilinus wrasses may be a different story.
Once added he may stay buried for a couple of days. Thats completely normal so dont worry if you dont see him.