Add hotter cam or Add hotter head ?

It depends on your long term plans. With a stock engine you can only move up one notch to a slightly hotter cam.
Define one notch up in cams size.
I’ll call BS on this one!
If you add heads / raise compression later the cam may not be enough and get wasted….
Depends on the grind of the lobes and many other factors.
depends how far you want to go. Heads won’t be a waste but may not add a ton of power on their own (like any component) I’d do nothing until you can add compression.
Not needed but would result in better results.