XCMS is transitioning to a new interface (new functions with different arguments, but that basically does the same) where centerSample is an argument to ObiwarpParam. That it doesn't work with center=NULL but does when you don't specify might be a bug; it should work I think.
I think the reason you don't get a plot is because you have specified plottype = c("none","deviation"). You should only use one of the two. Otherwise the first option is used i.e. none.
Yes, default values are used if you don't specify explicitly.