In this case it isn't about improving heat transfer through the bottom of the pan, it's about improving heat transfer across the bottom of the pan.
The heat will travel through the pan more slowly because of the added material, but due to coppers extremely high heat conductivity, the copper base will heat very evenly, even if the heat source is unevenly applied, and therefore evenly transfer that heat through the steel layer.
Yes it would. Adding material generally makes thermal conductivity worse. There is no material with negative thermal resistance, so adding more will always increase thermal resistance by at least a bit.
The only exception is 3D geometries, where an increase in surface area due to the extra material can outweigh the effect of the added material, and lead to a net increase in thermal transfer.
This can lead to a paradoxical effect, where ADDING insulation around a pipe leads to HIGHER transfer than with less insulation material, because the added material increases the exterior diameter, and therefore surface area.
(Heatsinks are also a good example. It is more material than just the component by itself, but increases surface area by such a massive amount that it more than outweighs the added material)
If you don't own a car, or can't drive (at the moment) for some other reason, in a lot of suburbs in the US you literally don't have a choice.
Where I live in Germany there's also a lot of supermarket delivery, but they're generally picked and delivered by people working directly for the supermarket, not random gig economy dudes of the street, so since they have access to the stores inventory system they will automatically know what is available (and since the order app also has that access, you can't even order anything the supermarket already doesn't have in inventory at the time of ordering), and either automatically cancel, automatically substitute or send you a notification to pick an option if something is out.