1) Take your shop out of closure for like 20 seconds. Once its open to public, go to
http://validator.w3.org/ and fix the errors regarding normal code like missing selectors, expecting certain things... That may clear up alot of issues.
2)
.product-details .image has a float: left; property. Removing that will put the description and such below.
3)
.product-details .details .descr has a padding-top: 130px; property. That will remove a huge amount of white space.
4) For multiple image rows, you can put a height property on the div class
Image
Enjoy.