At the start of of the Shadowwalker's turn, can he use Faithful Friend and then activate the familar before performing any actions with the hero?

Check out the card.

Faithful friend gets triggered during Step 1, part 1 (start of turn abilities.)

The activation of the shadow soul happens either RIGHT at the beginning of step 3 (perform actions) or RIGHT at the end of step 3.

So, yes. You can place him with faithful friend and still activate him before your actions.

You gotta love faithful friend!!

Just to clarify, the rule book says on page 17, "Essentially, a hero player with a familiar must choose whether to activate his hero first or his familiar first." and that card is called the Activation Card. To me, that implies the hero figure's start of turn happens after it has activated.

Edit: Nevermind, I found this: https://boardgamegeek.com/article/11588938#11588938

Just to clarify, the rule book says on page 17, "Essentially, a hero player with a familiar must choose whether to activate his hero first or his familiar first." and that card is called the Activation Card. To me, that implies the hero figure's start of turn happens after it has activated.

Edit: Nevermind, I found this: https://boardgamegeek.com/article/11588938#11588938

Wow that opens many new tactics. Never played it that way.