QIf I play Servant of Lust, then evolve it and play its On Evolve ability, does X equal 2?

AYes. You dealt 1 damage to your leader with Servant of Lust's Fanfare ability, then gave your leader -1 defense to pay for its On Evolve ability, so your leader has lost defense 2 times that turn.

QWhat counts toward "the number of times your leader has lost defense this turn"?

AFor example, if you deal 1 damage to your leader, that counts. If you give your leader -1 defense to pay for Servant of Lust's On Evolve ability, that counts.

QIf I play Wings of Lust and choose 2 options, dealing 1 damage to my leader twice, does "the number of times your leader has lost defense this turn" go up by 2?

AYes, it does.