Recording audio (book) and creating useable chapters to send via email using Garageband. Help!
Yes, you should break it up so that you can solve both problems. 

The easiest way to do this is to create another track and mute it. 

Then you can use the &#x2318; + T "Split" function at each chapter (if need)

Finally drag all the audio but the current chapter you are exporting into the muted track. (Use select all and then shift-click the chapter you want to leave behind to unselect just that one.)

Forgot to mention:

You will do one export for each chapter. 

In my experience when you export this it won't have a lot of silence after the end of the chapter, but if it does there is a UI element (I don't know the name) but it is a purple triangle in the time line that you can drag to the end of the audio you want to export.

It will take a bit, but you can do it. 

One last note: since it is spoken word, you can export it at a pretty low bit rate. I use the "Mono Podcast" all the time and it is fine.