Cut'n'paste guestbook w. umlauts & linebreaks

I need a guesbook script that uses three textareas, each that can be preformatted to give an output as follows:
First field: Headline in size 5 and bold
Second field: Text, size 3
Third field: Byline, size 2 and bold.
Another area should allow the submission of an URL, subsequently presenting an image (Could be omitted.)
The script should write over the previous file, creating a new file with the same name, thus replacing the old one everytime one uses the script.
There should be a password protected submission area only. No public access, except for the output.
The tricky part, i suppose, is to allow the textareas to maintain the line breaks and umlauts from the cut'n'pasted text, presenting them in a sort of "edited" form in the guestbook.
I have looked everywhere for a script like this, and have also been told that it can't be done. I thought i'd give it a shot here. X-perts here have helped me before
Algabatz