To boot your Mac into verbose mode, you need to hold down the Command and V keys during startup. To boot your Mac into safe mode, you need to hold down the Shift key during startup.
If you hold down both the Command, Shift, and V keys at the same time, your Mac will enter verbose mode but not safe mode. It is not possible to enter both modes simultaneously.
Scroll down until you get to "How to set an automatic booting Mac in verbose mode". You can use Terminal to make your Mac always boot into Verbose mode then, in theory, booting into Safe mode should work on top of that.
Yes. Enter sudo nvram boot-args="-v -x" in /Applications/Utilities/Terminal.app, enter your password and reboot. This will permanently enable both safe and verbose boot. To undo, enter sudo nvram boot-args="" in Terminal.