Buy the Novara Flyby ($600 less your discount), a helmet, and a U lock, and start riding. I suggested that folding model because it sounds like you will be taking the bike on the train. If you will not be taking the bike on trains/buses and have a long commute, then get the Zealo for ($700 less your discount). Have the bike shop guys figure out what size bike you need.

A year from now, you'll have a good sense of what you need/want and can buy another bike then.