Questions to Ask a Birthmom

We were matched with a birthmom back in december. We have been writting her letters. I am now running out of ideas as to what to write about. Anyone have some ideas? How deep should I go into talk about us preparing for the babies arrival? Is that a subject I should even approach? I don't want to offend her. I am at a blank. Please. any input would be useful. gonnabedaddy