Hello,
The only two kind of ring-necked subspecies found in Tennessee are Misssissippi and Northern ring-necked, they both feed on similar diet.
>Do I need to get a heat lamp for it?
Ring-necked snakes are primarily nocturnal, you will never find a ring-necked snake basking under the sun in the wild therefore you don't need to provide heat lamp.
>Is this a pet that is easily kept?
The answer depends on whether the snake willing to eat, The ring-necked snake is not a good beginner snake because it's shy and also very picky on it's diet. No doubt ring-necked is a beautiful snake and you can also condition the snake come out more often from it's hiding place with creative aquarium furniture. You also need to provide hiding place for the ring-necked such as rock, empty log or tree bark so it's life will be less stressful.
>Biggest problem I have, is that I'm not going out to scavage food for it, I'll buy whatever I'll need
Most northern ring-necked will feed mainly on salamanders which you will need to go hunting for the snake and it seems this is not an option for you. So I would suggest you get the earthworms either from the pet store or bait shop and give next four weeks to observe if the snake willing to feed on earthworm. If it refuse to take the earthworm then you need to release it before it starving to death. With a 9" ringneck, a three inches salamander will be enough for one week. Since the girth of salamander is bigger than the earthworm, you may need to give a bigger worm or few small worms to fill the ring-necked appetite. I use Zoo Med reptile carpet for the cage to make sure the snake won't ingest the substrate which could be fatal for the snake. Northern ring-necked will never take cricket, meal worm or slug as food.
>With winter time coming up soon, I need to know what to buy from the pet store to feed this little guy.
If you can't get the earthworm from the pet store or bait shop in the Winter, I would suggest you to start a small scale worm farming by yourself and it is really easy , all you need is soil in a small bucket and put the overleft vegetable or fruit for the earthworms to decompose. Also make sure you buy black soil without fertilizer mixed in it because the chemicals may harm the snake.
Hope this will help, good luck with you pretty ring-necked.