TDF questions re seating

Anyone know the inside scoop on how seat assignments work? I always kind of assumed they assigned the best available seats 2 hours before curtain and if anything sold up to 1 hour prior they’d reassign your tdf seat but… I would love to know more about how it all works.

All of my past tdf seats have been excellent but does it matter when you buy your ticket? Is it all random? Based on how many people in your party? Something else?

I noticed that the original group of merrily tdf tickets yesterday said seats may be in the dress circle, and that the dress circle has elevator access.

The group that is up now says seats will be in mezz or balcony and that balcony does not have elevator access.

Should I take this to mean that yesterdays group will be orch or mezz/DC and that todays group will be mezz/DC or balcony but no orch?

I would love to hear more about tdf from anyone who might know