Grounding the (unused) power layer of a 4-layer PCB
If you are going to get a 4 layer board, I'd suggest using the "extra" internal layer for power.  The solid copper plane will reduce voltage drops across the board, and the capacitance between planes will improve power supply bypassing.  You don't need to do much for this - just define the plane as Vcc, and it should automagically connect to all the Vcc vias and component pins.  You don't need to remove the now-redundant Vcc traces on the surface layer, unless you want to.