Backlog should clear in 3 days at this pace. New tasks are already being sent out, but "ready to send" is not consistently above 0 yet.

Out of curiosity, does the validation order goes by FIFO (first in first out) when quorum of two is met or based on work unit number or task id number?

It's ordered by the WU transition time, but this time is set in dozens of different places that follow different logic, and often to the same value for many WUs. So it's mostly random.

I saw that I'm getting no new tasks, and when I opened the project page it said: "Current progress (1021, part 4) 100.0000%", will there be a part 5?

From this forum message, it looks like it might not happen:

https://sech.me/boinc/Amicable/forum_thread.php?id=300&postid=2127#2127