Depends what you mean by old. I'm assuming a 4th gen still since that's what your profile shows you have. My guess would be no.... Yes a programmer will help get you better fuel economy but I don't know if it will bring it up to a 2013. There's more to fuel economy than just computer programming. It's the whole make up and flow of the engine as well.
These are just my thoughts though, someone else might be able to chime in with more information for you
I doubt it since the 25 MPG is based on the 3.6L, 2wd, 8 spd with the adjustable suspension, vent louvers and the improved aerodynamics that the 2013 have over the 1994-2012 models have
Unfortunately no. The new (for ram) V6 pentastar engine paired with the also new 8-speed transmission is what Dodge is claiming 25mpg for. If you are looking for more mileage, there are a few things you can do but it won't be cheap and the gains won't be tremendous:
Programmer (fuel mapping)
Exhaust/intake (helps engine breathe better a.k.a. more efficiently)
Tonneu/bed cover (aerodynamics)
smaller wheels/tires (less rolling weight/mass)