Newb Temp Question

I've had my egg for a little while and enjoyed some great cooks on it - Turkey, Chicken, Ribs, Pulled Pork and sausages. 

However my question is this: I had a three tier rack and the temp gauge was 275 on the middle rack (dome temp was 350). The top end with sausage was over done and the wings on bottom were a touch under done. Should I have placed the temp probe on top? 

Also...

I am going to do either a couple Butt roasts or brisket this weekend - where is the best place to set the temp probe? On the outside at least 2" away from meat? more toward the middle 2" away from meat?

Please help me on this - I know it is a basic question but I would appreciate the help.

Thanks in advance