Apple developer account and upgrading the OS

Question

I run OS 10.5.8 and I need to upgrade it to Snow Leopard or Lion so that I can run GameSalad.

I'll develop an app with GameSalad and upload it to the App Store.

As I understand, I need to pay $99 fee to Apple to upload apps.

Question 1: Is the following link the place I need to register to upload apps: http://developer.apple.com/programs/ios/ ?

Question 2: Is the $99 fee at that link the same fee that will enable me to download the latest versions of the Apple OS for free?

Question 3: Since I'm currently running OS 10.5.8, I can't access the app store -- first I need to upgrade my OS. Can I register an account at the above link before I upgrade my OS?

Question 4: With the account above, can I download Snow Leopard with my current OS 10.5.8 ? (Rather than get Snow Leopard on DVD). Bearing in mind I can't access the App Store with my current OS 10.5.8 .

(Or alternatively can I download Lion with that account? -- again bearing in mind I can't access the App Store with my current OS 10.5.8).