I don't think it matters which order it's done in. If you're already at or near your ideal weight for your frame, probably easier to start bulking. If you have weight to lose, I'd focus on losing that first and then putting good weight back on after the fact.
For food, it really depends what your goals are.
Bodybuilding.com has a lot of good diet ideas. Some people follow a ratio of macronutrients (carbs:protein:fat), some people count calories. I just measure all my food and make sure to have an easily absorbed protein based meal after exercise. I personally don't think all calories are created equal (ie. I think it would be better for your body to get 400 calories from a small entree of rice, chicken, and veggies than in 2 poptarts), but you've gotta do what makes sense for your lifestyle and budget.
This is what my daily meal plan looks like:
Breakfast smoothie (water + protein powder + banana + blueberries + strawberries + peanut butter)
Peanut butter and banana sandwich on Ezekiel bread
Sliced turkey w/ provolone cheese and kale on whole wheat tortilla
Celery w/ peanut butter
Yogurt
Post-workout protein shake w/ vanilla almond milk and spinach
Chicken breast w/ rice and sauteed vegetables
