Also Windows play a role in emergencies: "that sides on fire, let's open the other escape door"
The 50% lighter just doesn't work any way you spin it. I think this is another example of the journalist not really digging and verifying statements in a subject their knowledge is lacking/non-existent. (Similar to, "wine/chocolate/smoking/x cures cancer new study shows".)
You can't just remove all the fuselage reinforcements even if you remove the windows... Still, observe as mentioned in calculations [0], even the ~1% gain is significant as it accumulates over time.
[0] https://aerospace-europe.eu/media/books/CEAS2015_211.pdf
That seems extremely hypothetical and optimistic. If your large passenger plane is on fire you're probably already dead.
I think the types of things they would be looking for are flap deployment, icing, damage to the wing, gear deployment (though there is usually a window in the floor for this), etc.
There's a great YouTube channel called Mentour Pilot that covers a lot of stuff like this, but I can't find his video that discusses visual inspections.
https://www.youtube.com/channel/UCwpHKudUkP5tNgmMdexB3ow/fea...
It's also one of the requirements for starts and landings, along with "make sure your seat back and folding trays are in their full upright position".