You own an app
The form is faster: add the app and confirm ownership, and the card lands in your account. Write only if the form will not let you through.
Something on a card is wrong
Send the link to the page and what exactly is off. The numbers are collected automatically once a day, so a fresh jump can take a while to show.
Take a page down
Send the link and the grounds. If the app is yours and you do not want to be listed, that is enough.
Advertising and placement
Terms and the available places are on the Advertising page, and writing from there is easier: it shows what is free.