Full Moon: At the beginning of your turn, roll a d6 once for all friendly characters with the Full Moon trait. On a result of [1] - [3], Werewolf can use Shape Change. On a result of [4] - [6], click Werewolf to click #11 and click him to click #2 at the end of the turn or before he takes any damage, whichever comes first.

The Scent of Blood: If an opposing character has taken damage this turn, modify Werewolf's attack, speed, and damage values by +1.

How long does Shape Change last if I roll it with Full Moon?
Until you roll Full Moon again and the result comes up [4] - [6].

So if roll a [4] - [6] on Full Moon, I will always go to click 2? Even if my Werewolf was on click 4 and almost KO'd before?
Yes. You will always go to click 2 at the end of your turn or if the Werewolf is damaged. And, yes, this means your damaged Werewolf gets better... but also please note that nowhere does the word "healed" appear in this description. So game effects that would care about healing are not activated by Full Moon.

What is the duration of the modifier granted by The Scent of Blood?
This current turn. Any time you would go to check the Werewolf's combat values and look for modifiers, just ask yourself, "Was an opposing character damaged THIS TURN?"

If not, there is no modifier. If there was, modify away.