1:I want to reduce gap between image and tabs,I tried the method you mentioned in support but not very helpful.
What did you change, and what happened when you changed it? There are two different CSS files, one for dark and one for light. Did you change the appropriate one, and what happened when you changed it?
2:Content under the tabs got new text style font and all that ,Possibly it has own css file ,i dont want it to change text style font or color of font in content coz then it looks like very odd from the other text on web,For example if we dont add any tab text comes up normal but as soon as we add tab it become black and biggerin size.
It does have it's own CSS. You can change (or comment out) either /components/com_virtuemart/themes/Dynatabs/templates/product_details/includes/js/css/dark-hive/jquery-ui-1.8.5.custom.css
You are looking for this class:
ui-widget-content
For light versions, you could go here: components/com_virtuemart/themes/Dynatabs/templates/product_details/includes/js/css/cupertino/jquery-ui-1.8.5.custom.css
You can also use a different jQuery Themeroller UI version if you like, or roll your own. You just download the Themeroller package and upload it to the css/ folder
If you don't want to override the font settings for your template, just comment them out. Make a local copy of the files first, in case you make a mistake and break the template.
3:The add item grey box - is there any way to reduce its size or move it next to the image on top .
Are you talking about the add-to-cart box? It is 100% CSS driven, so you can put it anywhere you want it.