thephilm on "WP development locally - Error establishing a database connection"

Have you verified that the db imported successfully?
Check https://dev.mysql.com/doc/refman/5.5/en/getting-information.html for a few of the commands (though it looks like you already have a good grasp on that). Also - be good to make sure there are no restrictions with root access to the db.

It might even be worth writing a small php script to make sure to isolate the issue outside of wordpress.

<?php
$username = "root";
$password = "";
$hostname = "localhost";

//connection to the database
$dbhandle = mysql_connect($hostname, $username, $password)
  or die("Unable to connect to MySQL");
echo "Connected to MySQL<br>";
?>

Use this to make sure you can at least connect properly to MySQL.

Then -

<?php
//select a database to work with
$selected = mysql_select_db("yourdbname",$dbhandle)
  or die("Could not select examples");
?>

Use this to make sure you can connect to the actual database.

If both are successful, then you may want to recheck the wpconfig again for extra spaces etc.