How to get Node Title and description when nid is avaiable?
You can easily load the node using $node = node_load($nid);

Hoever it can be a bit tricky to get the values you want, so I recommend Entity metadata wrappers. They are part of the Entity API module and they allow you to access node variables like this:

$node = node_load($nid);
$node_wrapper = entity_metadata_wrapper('node', $node);
$node_wrapper-&gt;title-&gt;value();
$node_wrapper-&gt;field_description-&gt;value(); 


At the bottom of the linked Entity metadata wrapper page is a section on Debugging or introspecting wrappers, you can use that to find all available fields and their names.