If I play 'Way of the Force' on a 1 dice character (i.e. Tusken Raider) can I add a 2nd die to the card?

Yes, you have made it Elite. It works the same as when you play Training on (for example) a Stormtrooper.

Something that will probably come up with this card, that came up with training, is making elite. Way of the Force does not add a dice, it makes a character elite. So if the character is already elite the card does nothing. And putting two on a character doesn’t give two bonus dice. The only thing this card does is give you a second character dice if you only have one.