You can tap any untapped creature you control to pay the escalate cost, including one you haven't controlled continuously since the beginning of the turn.

If you choose the first and third modes, and destroying the creature ends an "exile until" effect (such as that of Lunarch Inquisitors), the creature will return to the battlefield before you put +1/+1 counters on creatures. The same is true if you choose the second and third modes and destroying the enchantment ends such an effect.