1. It appears that a 60-day trial of Office Professional Plus is available here: http://technet.microsoft.com/en-us/evalcenter/ee390818
2. DBXL is another product that will allow users to fill out and store completed forms, and provides a slew of features for processing and querying data from them. The InfoPath analog to Acrobat Reader is InfoPath Filler, but I don't believe it is available separately from InfoPath Reader. The alternative is to use SharePoint, which allows filling out InfoPath forms in a browser (with some features disabled).
3. I don't know of any OneNote integration in InfoPath.
4. The InfoPath client provides two controls for this - the Picture control, which allows users to attach an image and have it displayed in the form, and the Attachment control, which allows users to attach any kind of file.