Hello. I'd first like to apologise if this has already been answered, as Google wasn't too helpful.

Yesterday, I switched my payment mode from "Collected" to "Direct," while I still had about $100 worth of collected payments not yet processed (less than 7 days old) as well as one payout still in review.

I'd like to know if I'm still eligible to receive those payments, and what's going to happen.

Thanks for your time.

Yes, you still must claim those funds on your account by providing tax information and setting up a payout recipient account. Those funds can not be paid through anything related to the “Direct” payments system as they are completely separate systems.