You have to count all players on the 40 man roster for luxury tax purposes.
Correct, but you only pay guaranteed contracts. The way I read it is that minor league deals are basically set in value. If the player is not on the Major aleague Squad, they don't get the Major league salary incentive.
For instance, say you sign Jeremy Hellickson to a non-guaranteed 2M dollar contract. The tax hit of 2M only happens if he makes the 26-man roster. If he goes to AAA, he gets paid AAA money.
For 40-man guys in the minors, their AAV is a pro-rated portion of the MLB league minimum depending upon how many days they are on the active roster. Therefore if a guy is on the 40-man but spends the entire season in the minors their oth no callup, his hit against the tax is just his minor league salary.