PCB stackup plane distance
Well hopefully you don't have 1" spacing between your layers because that's a heck of a thick board :)   You can use layer 3 for small local power planes and routing but the consequences I can think of would be the following:


Traces on layer 4 will reference the reference plane on layer 2 if there is no reference plane below them on layer 3.  As you say the distance is greater, you won't be able to get reasonably sized traces and maintain the same impedance you have on layer 1.  Well unless the over all thickness is very small, but in a 4 layer board it won't be.
Your radiated emissions will increase because your loop area is increased
Traces on layer 3 will reference layer 2
Places where your traces on layer 4 cross your power planes will result in impedance discontinuities and reflections.  Depending on your speeds this may or may not be an issue for you.  I'd advise avoiding this, and where possible only cross traces on layer 3 and 4 orthogonally (like a plus sign).
Traces from layer 3 and 4 can couple to one another easily so avoid long parallel runs between the layers just as you would on a single layer.