Hi Jochen,
The problem is I don't know this sort of config stuff either (and hate it) - I'm a webdesigner/php/JS coder
I know it's extremely frustrating and a schande that VM is so poorly documented - but the VM forums are the place to ask - we just support our templates here...
re the colour I can help
in your template sonewhere is this stupid bit of code color: #636363 !important;
why over-write every colour???? hmm
fix it with in /templates/new_vision/html/com_virtuemart/assets/css/flexibleVM2Global.css ~ line 1601
color: #FFFFFF !important;
in the
div.checkout-content-cart a.FlexibleSelectShippingButton, div.checkout-content-cart a.FlexibleSelectPaymentButton, div.checkout-content-cart .billto-shipto a.details, div.FlexibleLoginBoxRight a.FlexibleResgiterButton, div.FlexibleLoginBoxRight a.FlexibleGuestButton{
block
there are some others but just use Firebug to find them
www.flexiblewebdesign.com/forum-virtuemart-2-template-puremart-support/342-using-firebug-for-customization-or-troubleshooting
cheers
oops sorry -
that image - parent - punks etc is on every VM admin->products->the product Custom Fields tab