Congrats! Dachshunds are my favorite!
Dachshund puppies should eat ~1cup - 1.5 cups a day. The main ingredient in whichever food you pick should be chicken. I've read and been told by breeders that this is the best type of meat for a dachshund, although I don't know exactly why. Dachshunds are prone to pancreas problems, so it could have something to do with how they process it. You'll want to get something with a smaller kibble size since dachsies are small. They can choke on larger snack items like biscuits, but I've never had one choke on kibble. I bought a 30 lb bag of food and it's lasted forever... I'll have to pay more attention to how quick it goes. I'll warn you now, dachsies are piglets. They will act like they are starving if it means they can get another morsel of food. Don't be fooled! As she reaches 1 year old, you'll need to keep her at 1 cup of food a day. Keep an eye on her weight and adjust accordingly. You should be able to feel her ribs easily, but she shouldn't be tiny either.
Your dachshund pup will need somewhere warm to sleep. If she is a smooth hair, she will get cold easily, especially during summer if you run the a/c. Be sure to provide a blanket for her to snuggle in. Dachshunds like to tunnel in blankets, even if they are crated.
As a breed, dachshunds love attention and will take full advantage if you baby them to start out with. Unless she is really well adjusted, be ready for some whining the first couple nights. If she does whine, don't coddle her or she will expect you to coddle her always. You're setting the stage for how your new relationship is going to be.
If she is going to be an only dog, you'll also need to keep an eye on her ears. For some reason I've noticed dachsies tend to get dirty inside their ears quickly if you don't wipe them out periodically (like once a month with a warm wash cloth).
That's all I can think of for now. I have 2 dachshund puppies right now, Harvey (~7months) and Rusty (~3.5 months). I've had dachshunds all my life (which hasn't been that long yet! *lol* ). If you have any questions, I know a lot about the breed and also know where to find most info if you need it
Oh yeah... As far as treats go, stick with smaller stuff. If the treats are big, just break them up. My pups love Pupperoni sticks and peanutbutter. As with any dog, practice moderation. They can be little beggars! I make my boys sit before they get anything.