Reserve....periods of certain days when you are on call to crew scheduling. Call out times vary...but are usually 90 minutes to 2 hours. Some companies have LONG call... 12 hours or so. Holding a line means your senoirity is enough to bid for scheduled flying...ie..not reserve.
As for houston...... thats probably a pipe dream at least for a year or two....maybe longer.... newhires generally going to Newark I would suspect.