What going to happen to Dulche De Leche during baking?
It will taste like dulce de leche.  It's already caramelized, so it's not going to change in most recipes.  If you cook it on high heat for long enough in a baking recipe, it will become a darker caramel, but that's it.

It will become more liquid at high heat, so you want to make sure you cook it "contained", like in an empanada or pie crust.  Otherwise it might drip onto the floor of the oven and burn.