Full export-import

Hi

I've a full working online shop but due to some url options and marketing issues I've to change it to another domain.

Detailed:
I've the webstore working at loja.jiatingsousa.pt/loja and I need to change it to www.jiatingsousa.pt/start where I've been already working on the design and stuff.

How can I do it without spending days?

Sincerely
Marco António Sousa

Update: I was able to do the copy by import-export SQL db and then change the joomla prefix of all joomla related tables.
Now I'm having another trouble... any product I click it just opens a blank page. Even if I create a new product, the same happens. Only blank page.

Any suggestion?