a: Even with rectangular pizzas sold by weight, the larger one is a better value than the small. Consider that the border of the pizza is a 2-3cm wide crust that will probably go to waste because eating that much white bread is awful. In any case, it lacks delicious cheese, sauce, and black olives or pepperoni.

The larger the pizza, the smaller the ratio of fixed width perimeter to center. If the area of the perimeter were to maintain a constant ratio to the total area, it's width would have to increase in proportion. That applies to any 2D shape, not just a circle or square.

In fact, the calculation in op is wrong because a 16" pizza isn't merely four times as large as an 8" pizza. The 1" crust makes the 16" really a 14" while the 8" is really a 6". 14^2/6^2 = 5.44 times as large.

b: If you were to say anything like that in the USA, you'd be reported to the TSA for un-American activities as soon as anyone heard you. And the NSA would hear you, even if you said it inside your own head. So bring a 100ml or smaller bottle of lube with you for the probe next time you fly.