Can you set a limit for faders in the mixer panel?
 
I want to record automation, if possible I want to set a limit for every instrument, like Synth -12dB, Bass -2dB, Drums 0dB... before I start automating.
 
Some kind of marker would also do, like a sticker.

You can create volume envelopes and save the track as a track template...
You can also group tracks with different volume settings and set to maintain their relative levels.

Toggle the Envelope/Offset mode button in the Mix module to Offset (button is 'lit', and '+' signs appear on Volume and Pan controls). Then set the desired limit/offset for each track and switch back to Envelope mode when you're done. Any automation you write will 'ride on top' of the Offset. If the Offset is -12dB, a 0dB envelope level will actually be -12dB at the track output.