Panorama displays images (including PDF) directly from the disk, they aren't store inside the database itself (no reason for them to take up space in memory all the time). Only the name of the image is stored in the database, or, if the image is in a different folder than the database, the path and the name (in which case the image can be anywhere on the drive).
In the case of PDF files, only the first page is displayed in the form. We will eventually be adding a PDF Display object that will allow multi-page PDF files to be viewed directly in a form. In the meantime, you can set up a button with a one line program that will open the currently viewed PDF in Preview.
Panorama doesn't know anything about the content of PDF files, so it cannot search the contents. However, Panorama can easily incorporate the results of any UNIX shell tool installed on your system. I seem to recall that there is at least one shell tool available that will extract the text from a PDF file. Unfortunately I don't have a link at the moment. With a tool like that, you could automatically extract the text and store it in the database so it would be searchable.
You can copy one cell from Excel into Panorama, or you can export Excel data as a tab or comma delimited text file and bring it into Panorama, but there is currently no way to directly transfer multiple cells from Excel and paste them into Panorama.