[bobcowan]

It's not uncommon to install them upside down. There is a very slight weight advantage to moving unsprung weight to sprung weight. But it's so small it's not worth talking about. The real reason is just to get it to fit right.

Tire pressure is generally 1 psi per 100 pounds of total car weight. That's a good starting point. On street tires, I generally run about 24psi, set with a tire pyrometer. But differant tires need differant pressure, so you my find 22 or 26 works better.