I have uploaded 50 meg PDF's to servers, but the php upload limit was at 100M on the server. No timeout issues.
Yes you need to add an image icon to the webserver.
Upload To: gallery/images/file_pdf.gif
AdminCP => vBGallery => Edit Filetypes
- Add Filetype (button)
Maximum Filesize: 2000000
Enabled: [ x ] yes
Maximum Filesize: 2000000 (2 megs)