VTA setting up.....how do I find level?

I've read advice to "raise the rear of the tonearm .03 inches from level" for best performance of my Lyra Helikon cartridge.

OK, how do you find level? If I place a bubble level on the tonearm it stresses the stylus with the extra weight! (damage potential!?) and bends the arm down, so it's not in the normal playing position.

Then, the numbered barrel on the JMW12.5 arm indicates what? (numbered 0 through 99)

Could someone address this particular step of the setup please?