Pdf aS a background
 

Og is great.
It would be better if I could open a PDF as a background.

Doesn't seem like you can do that yet. While you wait, a few workarounds:

If you have OG for the Mac, you can open a blank document, insert the PDF, save, then transfer to the iPad via iTunes or email or whatever.

If you don't have OG for the Mac, open the PDF in Preview, save a copy as PNG, email the image to yourself, read the email on the iPad, tap and hold on the image to copy, then paste into OG.

Be sure to send in your feature request via the Contact Omni entry under the Omni menu.