We've learned that vor is a two-way preposition, so it could go with Dative or Accusative. Usually Accusative is much more common for these fixed verb-prep-combos, but as the color in the examples already hinted at, the vor-combos all go with Dative.

Is it dative or accusative?

In the simplest terms, the accusative is the direct object that receives the direct impact of the verb's action, while the dative is an object that is subject to the verb's impact in an indirect or incidental manner.

Is BIS accusative or dative?

*Note: The German preposition bis is technically an accusative preposition, but it is almost always used with a second preposition (bis zu, bis auf) in a different case, or without an article (bis April, bis Montag, bis Bonn).