If I delete a paid app on my iPhone?

Will I be able to get the app on my iPad without paying again?

Ya you can just look it up again an it will be there. Or you can look in recent purchases.

You will not have to pay for it again as long as you use the same Apple ID that you bought it with.

You will lose the data if you delete it. Do you use your computer along with Pages in order to transfer your files into iTunes and the to your computer?

If you use file sharing you can transfer all of the documents before you delete the app. Read about iWorks file sharing here.

http://support.apple.com/.../kb/HT4088