Get Url in code:

Mage::getBaseUrl();

Mage::getBaseUrl(Mage_Core_Model_Store::URL_TYPE_SKIN);

$this->getSkinUrl('images/imagename.jpg');

$this->getSkinUrl('images/imagename.gif', array('_secure'=>true));

Mage::getBaseUrl(Mage_Core_Model_Store::URL_TYPE_MEDIA);

Mage::getBaseUrl(Mage_Core_Model_Store::URL_TYPE_JS);

Store Url: Mage::getBaseUrl(Mage_Core_Model_Store::URL_TYPE_WEB);

Current Url: Mage::helper('core/url')->getCurrentUrl();

Using CMS page:

{{store url=""}}

{{skin url='images/imagename.jpg'}}

{{media url='/imagename.jpg'}} 

{{store url='mypage.html'}}

Get current CMS page urlkey: Mage::getSingleton('cms/page')->getIdentifier() 

Create block programatically: Mage::app()->getLayout()->createBlock('mycalendarevent/calendar')

then can setTemplate, if in template file you may need get HTML data so <?php echo 
echo $block->toHtml() ?>

In template file can use $this->getLayout() instead of Mage::app()->getLayout()

Call static page:

<?php echo $this->getLayout()->createBlock('cms/block')->setBlockId('indentifer')->toHtml() ?>

$block = Mage::getModel('cms/block')->load('identifier');
echo $block->getTitle();
echo $block->getContent();