For your first problem:
What's the column type for the date entries?
I guess you have set it to "varchar" or something like that.
You should set it to "date" and insert the values like "yyyy-mm-dd".
In your portfolio page (=results table) you have to convert the date form "yyyy-mm-dd" to display like "dd.mm.yyyy".
You can do this in the bindings panel in dreamweaver --> select the date column and change the date format to "MySQL Date/Time: 30.12.2002"
There's a free dreamweaver extension at document.php?id_doc=51 which can do all the needed conversions.
Then you sort your recordset according to your wishes.
Your second problem:
the page shows a javascript error:
Meldung: 'Spry' ist undefiniert
Zeile: 291
Zeichen: 5
Code: 0
URI: kontakt.php?invalid=true
So maybe, that's the reason for the validation to fail. Just a guess however.