Your question:

except for the 1024. What is its purpose?...

Following the principle of RTFM, I've typed this in my shell: 
> perldoc -f read

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And received this, which is exactly the answer you were seeking there: 
     read FILEHANDLE,SCALAR,LENGTH
             Attempts to read LENGTH bytes of data into variable
             SCALAR from the specified FILEHANDLE.  Returns the
             number of bytes actually read, "0" at end of file,
             or undef if there was an error.  SCALAR will be
             grown or shrunk to the length actually read.  If
             SCALAR needs growing, the new bytes will be zero
             bytes.  An OFFSET may be specified to place the read
             data into some other place in SCALAR than the
             beginning.  The call is actually implemented in
             terms of stdio's fread(3) call.  To get a true
             read(2) system call, see "sysread".

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Remember, let 'perldoc' be thy oracle at all times of trouble! ;)

For your second question, I'm not aware of any Perl module that would allow you to implement a progress bar inside your web page. I guess this could be done by writing your current program progress to a file and displaying this file inside a continually refreshing page. The way you could track your program's progress, however, is discussed in the Progress Bar thread. I hope this helps ;).

_____________________ 
$"=q;grep;;$,=q"grep";for(`find . -name ".saves*~"`){s;$/;;;/(.*-(\d+)
+-.*)$/;$_=&#91"ps -e -o pid | "," $2 | "," -v "," "]`@$_`?{print"
++ $1"}:{print"- $1"}&&`rm $1`;print"\n";}

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In reply to Re: optimization of browser upload by vladb
in thread optimization of browser upload by Baz

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