If you intend to do any riding of any length, you'll need to add some carbs back into your diet. Bonking is really a drag.
Congrats on your new love! Straps (aka "clips") are OK and if they come with the bike, probably a good idea. You'll want to graduate to clipless eventually. For now, practice good pedal strokes (pedal in a circle, much easier to do with clipless) so you teach your muscles good habits. Go slowly (e.g., don't increase your mileage drastically) so you don't get hurt. Your tendons and ligaments will take longer to get strong than your muscles. Spin, spin spin. Don't push big gears yet - let your body adjust.
And keep in touch with this board. Lots of good advice from womyn who have been around (like a bicycle wheel...get it? OK - big groan...)