setting up ipad as new ipad or back up from another device I connected my ipad to the computer for the first time. I tunes showed up and asked me if I wanted to set it up as a new ipad or back up from a previous iphone that is no longer working. 

Although there are things from that iphone that I would like to be able to retrieve ( some purchased books etc ) I am not sure I want to back it up completely from the old iphone. 

However I am afraid that if I set it up as a new ipad then I won't be able to retrieve the stuff from the old iphone I would like to keep.

Main question really is if I set up as new ipad would I ever be able to retrieve any thing from the old iphone?
Your content that is stored on the cloud (apps, music from iTunes Store, etc.) can all be retrieved from the cloud as long as you use the same Apple ID to connect to the Store.

Other content from other services (e.g. Kindle books in the Kindle app) can similarly be downloaded from their providers.

Only content that was copied manually (e.g. synced from iTunes on your computer) would need replacing the same way you copied them to the iPhone previously.