I ride 11 miles each way to work, about half through relatively quiet suburbs and half through very busy city streets. It takes about 40 - 45 minutes each way. I personally would not bike to work if there weren't showers, as (especially during the summer) I sweat puddles on the ride.
Before you cycle in traffic make sure that you're comfortable starting/stopping/turning on your bike. There is a bit of a learning curve to riding traffic, but after a couple months you'll get the hang of it. Learn when to take the lane, look well ahead for obstacles so that you're never swerving out in front of cars at the last moment, signal your turns by pointing in the direction you're going (most drivers don't know the proper bike hand signals).
I've used a hybrid and a road bike for the commute. A road bike makes the commute faster and easier. A hybrid puts you in a more upright position and tends to have wide handlebars, so it's easier to learn on.
Fenders are nice to have when it's raining, and when the road is wet after a rain. They're must haves for the winter.
Use safety equipment. Always wear a helmet. Run a light on the front and rear of your bike any time it gets close to dusk/dawn or is overcast. When in doubt, turn them on. Wear fluorescent clothing in low light conditions. Wear reflective stuff. Make sure your brakes are in working condition.
Carry the minimum you can get away with. Keep your heavy U-Lock and cable locked at your office bike rack. If you can, bring your spare changes of clothing in to work on Monday, and pick it up on Friday. Keep a pair of shoes at your desk. What you do need to carry: A mini pump, a multi-tool, a spare tube, tire levers (depends on your rim - often you can get away without them, but better safe than sorry), your lunch. That's pretty much it.