Anton--
For turkey: Remove any excess fat from the turkey when you remove it from its package (take off the wing tips too, if desired (I do); save the fat and wings separately. Brine the turkey then make sure you rinse the bird well when you pull it out of the brine. When you make your rub, make it without salt or use just a pinch. Spray or coat your drip pan with oil. Add to the pan the reserved fat and wing tips and a cut up onion, stalk of celery, and perhaps a piece of carrot and a few celery stems. Normally, for an oven, I add just a little water, wine, stock, or a mix, to keep the aromatics and drippings from burning and replenish as needed. In the WSM or kettle--since I don't want to remove the cover while cooking--I add more liquid so I can be sure I won't have a problem. You can't really put too much liquid in. YAt the end of the cook you can pour off and save most of it, reduce the rest on top of your stove and create fond, deglaze with wine or stock, and make gravy from there, adding your the saved drippings you poured off.
On your other question: Rendering is greatest in the last half of the cook.