Jet fuel nor office furniture burn hot enough to melt steel
No steel was melted, the trusses were deformed (this occurs at about 500C) and sagged, which drew in perimeter columns.
The towers fell at almost free fall speed,
They did not fall at FF speed. They took 14-16 seconds, which if you do the calculations, is above FF.

This picture (below) clearly shows dƩbris and perimeter columns travelling faster than the collapsing building.

encountering NO resistance from undamaged floors below as it fell.
transfer of kinetic energy (which increased as potential E was lost) as the floors fell
Building 7 was "pulled" the same day (on 911) (now that's a pretty quick demolition job!)
If you read the exact Silverstein quote, he meant evacuate.
I remember getting a call from the Fire Department commander, telling me they were not sure they were gonna be able to contain the fire, and I said, you know, 'We've had such terrible loss of life, maybe the smartest thing to do is just pull it.' And they made that decision to pull and then we watched the building collapse."
Silverstein (La citation en complet)
L'officer du NYFD ni Silverstein ne sont dƩmolitionneurs, il veulent dire Ʃvacuer, pas dƩmolir.
puffs of white smoke came from base of building and all over higher floors as it fell.
Due to compressed air smashing through windows ejecting dust
The twin towers, built to stand after several plane collisions, collapsed by fire.... the ONLY TIME IN HISTORY a steel building has collapsed due to fire before and after 911.
The ONLY TIME IN HISTORY a plane hit buildings like these towers.