I am roasting a chicken for the first time. It's smallish just under 4 lbs. I want to roast it over brussels sprouts and sweet potatoes. (Does that combination sound alright?) I will be cooking the chicken in a v-shaped rack over the vegetables. Will they cook together at the same time? Do I need to start the chicken and then add the veggies? I was planning on starting with high heat 450 for the first 15 minutes and then dropping down to 375 for the remainder or the time. Any ideas/assistance would be greatly appreciated!