If possible set Shipment Free for some sku or single category?
not natively but something like the rules based ship plugin will work
or do a bit of coding in the std weight/zip plugin to do it..
You can help me? I don't know as do....
we are a business - if you want to hire us fine.. but asking for bespoke coding of your site isn't really fair...
Have a look at shipping by rules: http://forum.virtuemart.net/index.php?topic=112127.0