Create a keyboard shortcut for normalizing audio

Is it possible to create a custom keyboard shortcut to normalized an audio clip to 0db?
Is there any advantage to normalizing a group of clips that have varied peaking/volume at the same time by group selecting them and going through the normal normalizing process?

The keyboard shortcut is available. The normalise dialog box will remember the last used setting. Keyboard mapping can not select values in the dialog box. I don't understand the second question.

If by 0db you mean at the top of the meter scale, that is 0dbfs (0db full scale). You should not normalize your audio to 0dbfs as this will not allow for any headroom and could lead to clipping. If you are intending to normalize clips on separate tracks and then mix them you need to apply some gain staging. In this case I would suggest you normalize to the faders unity gain setting of -10 dbfs which will give you room to manoeuvre when mixing.