If you are looking for a document editing app, you can try Google Drive (formerly Google Docs), Quickoffice (which is also owned by Google), Kingsoft Office, and Smart Office.
Yep! Excel is compatible with the Nexus 6. You can download it in the Play store.
You can make Word documents with the Google Drive app, or the Quickoffice app, a third party app that's owned by Google.
I was faced with this dilemma myself upon purchasing a Nexus 7 last fall. There is no built-in camera app on the Nexus 7, but there are two options that worked well for me. 1) you could go to Google Play and download the free Camera Launcher for Nexus 7 app from developer MoDaCo. (https://play.google.com/store/apps/details?id=com.modaco.cameralauncher) 2) Download the popular photo sharing app, Instagram, also available from Google Play. (https://play.google.com/store/apps/details?id=com.instagram.android) Don't expect great results when you take photos with the front facing camera on the Nexus 7, as the resolution of the camera is a mere 1.2 megapixels, and it's a little tough to get a good photo of anything using the front-facing camera. Well, unless you're only wanting photos of yourself, then it'll work just fine.
You can either use that app, or you can also use Google Docs or Microsoft Word from the Microsoft Office Mobile app.
Yes, Buy them in the Play Store and download them with the Google Play books app.
Much like a camera app on an Android phone, the Nexus 7 also has its own camera app. If you have the 2012 Nexus 7, it has one front-facing camera. On the 2013 Nexus 7, you have a front- and rear-facing camera. The app is defaulted to the rear-facing camera, but it can be toggled depending on your needs.
Your photos can either be in the Gallery app, you can also access through the Camera app, access it (in the cloud) through the Photos app, or access it through Google+.
Yes, you can use the Nook app, which is available on Google Play.
Yes it can. You can play it back either by using the Google Play Music app, or you can find a third party player app out there.
Simply search for Google Play Books, and you will be able to re-download the app. This goes the same with the Amazon Kindle app.
It appears you can only delete the auto backup pictures from the desktop version of Google+, while leaving the picture stored in the Nexus 7. If you want to delete the pictures from the Nexus 7 itself, you can do this through the Gallery, Google+ (Photos dropdown), or the Photos app.
Just locate the Messaging icon (a rectangular bubble with a smiley face), click it and the app should launch. If the Galaxy Nexus has Android 4.3 OS installed, the Messaging app has been integrated into Google Hangouts, and is now a circular bubble with a quotation inside.