How to Get Customer Default Shipping Detail Using Customer Id in Magento

If you know the customer id than direct use it other wise first you can get customer id than use that.

$customerId =2; // already known

Mage::getSingleton('customer/session')->loginById($customerId);

$customerAddressId = Mage::getSingleton('customer/session')->getCustomer()->getDefaultShipping();

$address = Mage::getModel('customer/address')->load($customerAddressId);

$address_data = array (

            'prefix' => $address->getPrefix(),

            'firstname' => $address->getFirstname(),

            'lastname' => $address->getLastname(),

            'street' => $address->getStreet(),

'city' => $address->getCity(),

            'region_id' => $address->getRegionId(),

            'region' => $address->getRegion(),

            'postcode' => $address->getPostcode(),

            'country_id' => $address->getCountryId(),

            'telephone' => $address->getTelephone(),

            'email' => $address->getEmail()

);