Trace width & vias for PCB carrying 15vdc/1a
You are correct, the widths are listed in inches so "0.016" means "0.016 inches", or 16 mil.

IPC-2221 generally governs trace widths for given currents. There are numerous calculators that can be found online that will tell you what your trace widths need to be based on IPC standards. Here is one of them, from Advanced Circuits:

http://www.4pcb.com/trace-width-calculator.html

You don't mention your copper weight or allowed temperature rise, so it is very difficult for us to be able to tell you if your width will be enough.

As for vias, I would use the calculator to determine the trace width, and use that width as the hole diameter for the via. I would then make the pad diameter twice the hole diameter, and I would use one via for every 1/2 amp, so 2 vias in your case, for every trace connection/termination.