Hacking is as yet unconfirmed in PlanetSide 2.
There will be no vehicle hacking in PlanetSide 2. This decision appears to have been made in the interest of balance.
As the empires will be quite significantly different, you will not be able to use weapons and vehicles from enemy factions.
There is also a texture budget to consider. It seems the game's texture footprint is already quite large and having three times as many textures for everything (one for each faction) is not possible.