-Your workouts should be intense and challenging even if you don't want to be enormous. Getting huge and bulky takes a very very long time, you won't just wake up one day and have too much muscle for your own liking.
-I'd reccomend going to
www.fitday.com, it's a free registration, it'll help you figure out how many calories you're burning in your day to day routine and how many you're eating. Even if you don't use it everyday, it's very helpful in telling you how you're doing calorie-wise.
-Yes you can lose fat while building muscle, it's just a slower process than focussing on one. I'd reccomend a caloric deficit of 300-500 a day.
-Supplements-wise, you'll want a vitamin and whey protein, nothing else is worth the money when you start (maybe not when you're advanced either, it's debatable).