In the special setup of the Canyon Run mission of the Twin Shadows mini-campaign it is stated that "You may not use other abilities." while attacking with the Tusken Raiders (the only usable ability being spending a surge for +2 accuracy).

Does the +1 damage and re-roll granted by the Optimal Tactics card from the Inspiring Leadership deck count as abilities for the purpose of the special setup?

All text on cards and hero sheets are referred to as abilities.

Abilities provide special effects that can be performed above and

beyond the standard rules of the game.

Yes, they are abilities. (And it's not really special setup, it's a mission rule set up by mission briefing.)

+1 dmg of a deployment card is text on a card as well and may not be used with the attack specified in the mission rule.