Short answer, no added fuse needed on the power side of the coil.
The kill switch if it was wired to ground and the negative side of the coil would be like the points being closed. Normally on a running engine the points are opening and closing and the amperage draw is less than if one turned on the ignition without the motor running and the points were closed. On a running engine the coil might pull a couple of amps and then if the motor was shut off but the ignition left on, the draw might be a tad more providing the points were closed BUT if the points were open, then no draw as the circuit is not completed through the coil.
Per some information from the GM Heritage site on a Nova (sorry but this is what I have bookmarked for my own use) is that the ignition coil shows amperes drawn with engine stopped 4.0 but when running at idle, 1.8
While you can wire kill switches on the power side or negative side of a circuit, I prefer opening up the power side. There is no real right or wrong side and I've done it on either and/or both sides depending what I feel is the best.
However you do it, make it safe and run the wires properly so a short cannot occur between the coil and the added switch of yours.