Is Longitude Easting or Northing?

After transformation Latitude is denoted by Y (northing) and Longitude by X (Easting). The most common units of measure in projected coordinate systems are meters and feet.

Are Northings and Eastings the same as latitude and longitude?

"Easting and northing" are the standard names for the x and y coordinates in any projected (i.e. planar) coordinate system. Additionally, "latitude and longitude" are the standard names for the coordinates in any unprojected (i.e. geographic) coordinate system.

Is negative longitude east or west?

Latitude/longitude coordinates follow a regular Cartesian system starting from the Equator and the Prime Meridian. Positive coordinates are to the right (east) and up (north). This means that the Western Hemisphere has negative longitudes.