IRA for IRC 30D EV Credit

IRA Credit for 2022 EV
Under the transition rules for IRA for the IRC 30D EV credit, if I have a prior to 08/16 purchase agreement for an eligible 2022 vehicle but did not take delivery of the car yet, I can still claim old credit. It would need to be treated as if it was purchased prior to 08/16. In this situation 
1) What kind of paperwork do I need to show for claiming this during Turbo tax 2023 season?  I have a signed purchase order from March ‘22 with a $1000 deposit that says “Not binding unless not signed by dealer”. Is this sufficient? Or do I need to make an explicit purchase agreement before 08/16 with a 5% deposit?
2) Is the credit for Toyota brand vehicles subject to any phaseout after 09/30? Since the IRA came into effect would it stop the count for 200k vehicle limit?
 
I am anticipating that I will take delivery and complete registration for a 2022 Toyota RAV4 Prime in month of October.