you can add more icons by placing the image files in the repository/images/icons folder. by default the module will look at the file extension, then look for a coresponding icon. it will look for a .png first, then a .jpg and finally a .gif. If it can't find a match it will use 'unknown.png' as the icon. So if you want a special icon for .pdf files, create a 'pdf.png' or 'pdf.jpg' or 'pdf.gif' image, whichever you prefer and place it in the icons folder. the default size is 16x16, but you can change the size by adding settings named height and width to the FILEICON token in the .xml file and setting their value to whatever you wish. You can also set a DOWNLOAD setting to 'true' on the same token to enable download when the user clicks on the icon instead of displaying the icon full size in a popup windows (the default behavior)

in 3.01.14 you have a couple more options for your form.html files. instead of using [FILE] and [IMAGE] tokens for uploading, you can use [URLCONTROLFILE] and [URLCONTROLIMAGE] which renders the core Url control and allows people to upload new files and images or select from existing files and images.