Thank you for your questions.
For question 1, Could you test your files with virtual printer (such as PDF printer)?
Also, could you please upload an example of such a file here and post back with the link for me to investigate?
For question 2, you can import a PNG file as symbol.
Step1. Open a PNG file with DR (Design Review) and save as a DWF file.
Setp2. Open an existing DWF which you want to insert the PNG file. On the Markup panel, click the "Symbols" button and select "Create Catalog". Select the PNG file you just saved. In the popup dialog, select "Import each sheet as symbol". A message dialog will pop up and tell you the symbol has been created successfully.
Step3. Click the ‘Symbols' button again and select the symbol you just created. Move your mouse to the position you want and click. You will see your PNG file has been inserted into the existing DWF file.
Step4. Select the "select tool", zoom in/out the symbol and put it in suitable place as you want.
Please let me know if you have any follow-on questions.