As for frosting the cupcakes, I was worried that both would be difficult to frost for different reasons. The Cupcake Plunger Method results in giant cracks across the top of the cupcake -- I was worried that crumbs from the cracks would get mixed with the frosting as I tried to spread it across the cake.
The Spatula Nub Method, on the other hand, leaves your cupcake top pretty smooth. But since the Nutella is kinda just sitting there not being covered by any cake, I was worried that it would mix with the frosting and leave weird Nutella streaks as I tried to frost the cupcake.
But thankfully, neither of these scenarios occurred: I was able to frost both cupcakes without any problem:
Anyway, if there's anybody out there who has a better method for putting filling inside cupcakes, do share! I'd love to hear all about it.