> I would like to see an invoice, and have a link to the pictures, report file (word / excel file), and the pdf file.
With FMP, you may soon discover that you can do away with the Word and Excel files. The text/numerical data in these files could be stored in FMP tables and fields, and you can generate, format and print reports of this data whenever you need, without having to save them as hard files all the time. FMP can save such reports as PDFs too, if you want.
Images can be kept in your folders and "referenced" from within FMP or they can be imported directly into a "container" field in FMP. In either case, you'll still "see" the image within FMP. If you have lots of images (and it sounds like you do), "store only a reference" is the recommended method for working with images, otherwise the file size of your database can quickly become huge.
> search by invoice number, customer name, project name, etc etc.
Easily done in FMP.
I reckon download the trial version and go have fun!
When you download the demo you will be able to create databases from the templates included, some are good, some adequate.
There are Open Free databases available that are very good, very specific and somewhat more complex to customize
White Paper for Novice FMP Users