How much more care does a chihuahua puppy require than an adult?

Dog Breeds and Training blog

I'm planning on adopting a chihuahua soon and she will be able to come home with me in February. I will be going to school three days a week for a few hours. I understand that a chihuahua is okay for a few hours on it's own, but is it any different when it is a puppy of 12 weeks? Will there have to be someone there with it ALL the time until it is older or will it be okay? Also if anyone has any experiences with raising a puppy i would appreciate advice. Thanks!
I really appreciate the advice i'm getting, but if anyone could i'd appreciate more on the main question. Would a young puppy of 12 weeks be able to be alone while i'm at school? I've heard they need to be taken out to pee almost every hour.

hello! Great choice of dogs! As you can tell from my name I am a big Chihuahua fan. I have been raising them for over 8 yrs. The main thing with a chihuahua is to make sure they don't get low blood sugar(hypoglycemia). The best way to prevent this is to free feed them, leave their food out in front of them all day. They eat small meals, but eat often..They are fine if left for a few hours a day, just like any dog. They are very fragile. You have to watch where you walk, sit, or lay down. They like to climb too and can easily hurt a leg by faloling off the back of a chair or couch, or out of your arms. It is best to leave them in an x-pen while you are at school. Here is a link to what I am talking about.

http://images.google.com/images?q=dog%20exercise%20pens&ndsp=18&svnum=10&hl=en&lr=&rls=GGGL,GGGL:2006-18,GGGL:en&start=0&sa=N

They are big enough to hold a bed, water/food bowls, puppy pad or even a litter box. Enjoy your new puppy when you get it!