Regarding All-Out Attack.
Scenario:

Bumblebee-TL tapped in bot mode, Prowl-MS and Cliffjumper-RW untapped in car mode.
I play All-Out Attack. Cliffjumper attacks and uses Anticipation Engine to trigger a Start Your Engines. Bee flips to car mode, Prowl is irrelevant, Cliffjumper untaps. Using Bee's extra action via flip to alt mode, I play Ready for Action to untap Bee. Cliffjumper finishes his attack. All 3 cars are now untapped.

Am I free to attack again with Cliffjumper?
Am I free to attack with Bee?
Am I free to end my attacks when I choose because of AoA?

All-Out Attack says Each of your untapped Transformers (Editors Note: Characters) can attack this turn. At the time you play All-Out Attack, check which of your characters are untapped. Those characters are allowed to attack this turn, in sequence. They are not, however, required to attack. They cant attack a second time unless your opponent is tapped out. As usual, you still must attack with at least one character during your turn if you are able.

Source: Wizards of the Coast (2019-09-06)    【Link to Ruling】

Tags: All-Out Attack, All-Out Attack, All-Out Attack