Breath to your lower back.  This is the bottom of your lungs.  You can even tense your rib muscles to get more air in.  Relax everything when you sing.  Pushing your stomach out when you breathe is incorrect.

Singing a verse is done with a continuous breath the same flow rate and pressure. Subtle variations of this rule will be necessary depending on the song or beat, but that is the general principal.  You can lean forward a little at a time as you sing out.  This is the technique opera singers use (appoyo).

Hold your breath as long as you can. Time yourself. Work up to holding your breath and not breathing for several minutes.