2 iPad app questions.

the split was by accident, I don't know what I did. How does one open a book or 2 distinct books on the iPad app?

David - 

The screen shot below shows a "semi-circle" which is a slider to open and close the split screen mode. The slider is ALWAYS present. 

Although Notes would be nice, I would like highlights first -- even those created on the Mac version being downloaded if I save a book to the device. I assume since they did not appear, this is on the to-do list

Notes and Highlighting are on the "to-do" list, as you said. One difficulty is the syncing, which is a major component of the next version "4.5," (which will begin beta soon). Currently, syncing works pretty well between computers, but really poorly on the mobile apps. If you have a reading plan, I would not encourage you to mark "read" on your mobile app. There is a good chance it will create a duplicate reading plan on your computer. Also, you will soon notice that your reading plan on you iPad and computer are "out of sync" in terms of "marked as read." We are all anxiously awaiting 4.5 to improve this.