They are sort of like a more intelligent version of the PVV, focused a bit more wide instead of almost only (at least publicly) on the immigration problems like the PVV. They'll have some problems though, they won more seats than they have people to fill them
Why especially those two provinces, no idea. Probably because they're good in cities, but cities are generally more left (especially Amsterdam is as left as PVV is right), so that's odd. They were even the 3rd biggest in my town, only slightly behind the ever dominating SGP (super strict Christians who often don't for politics but just for religion) and ChristenUnie (more relaxed Christians).