some general gas oven questions

i pride myself on being a good cook. however, for the last 20+ years i have been using an oven that barely fits a med. roasting pan...it was a gas oven from 1953 with a side storage oven. i am now the proud owner of a bluestar 30". it's about 3x the size of my old oven and i find myself with some questions that i am hoping you might help me with:

1. convection and roasting. (needless to say, my first go'round with convection). always use it? only with baking? (of which I do little but i roast and oven braise a lot). any fine tuning advice on this is good.

2. cooking multiple items: i'm thinking ahead to tgiving when we are going to have a group. hurrah i'll be able to fit a large turkey (at last!) but am wondering about putting in a casserole of sweet potatoes or the pan of stuffing. will it bring down the temperature fast if i add these items in while the turkey is roasting?

3. big oven ....roast on a rack positioned lower or keep it centered in the oven?

thanks for any advice or tips. i've been starting out slowly ...roasted basalmic lemon chicken legs and last night some pork tenderloins (for that i used the convection fan and 500 and felt it cooked faster than i anticipated (i usually do 10 min. and then flip and 10 min. til the pork goes to 140 degrees then let it sit for 10 min.)

ok....looking forward to responses.

bean