Q1 - As pointed out above, CGI.pm saves uploads to a temporary file so it can handle any file size as long as you have disk space left. I've handled over 600 Mb files with it without any problems except buggy Internet Explorers :-)

Q2 - I never noticed that callback, but you probably won't be able to do the notification very efficiently in a CGI. What I do in situations like this is: on form submit I show an animated gif indicating the upload is taking place:

<form ... onsubmit="document.images['imagename'].src='animation.gif';"
+>
 ....
</form>
[download]

Or something like it (can't remember the excact javascript now)

It's a lot easier and looks almost as good :-)

Joost.