Yes, you can put arrays in sessions, example:
$_SESSION['name_here'] = $your_array;
Now you can use the $_SESSION['name_here'] on any page you want but make sure that you put the session_start() line before using any session functions, so you code should look something like this:
session_start();
$_SESSION['name_here'] = $your_array;
Possible Example:
session_start();
$_SESSION['name_here'] = $_POST;
Now you can get field values on any page like this:
echo $_SESSION['name_here']['field_name'];
As for the second part of your question, the session variables remain there unless you assign different array data:
$_SESSION['name_here'] = $your_array;
Session life time is set into php.ini file.