A suspension fork isn't required for your purposes and more than likely lead to a false sense of security off road, encouraging you to go beyond your skill level. You may choose one for comfort, however, just make sure it has a lock out feature for the pavement.

Disc brakes comes in handy if you're riding in anything wet- mud, rain, snow, icy sludge, or long, steep down hills. Some hate on them, others swear by them, so it's gonna be a totally personal preference issue.

Wider tires offer more of a cushion, reducing the amount of air pressure can improve the ride quality a bit, but you don't want to run too low of pressure on any given tire or run the risk of pinch flats.