Do Puppies Need Their Shots?

Absolutely.  Watching a dog die from one of the diseases they could have been vaccinated against is extremely sad, and rabies vaccines are a must, especially if the dog is going to be outside at all.  You never know when your dog will bite you, or someone else.  The shots are easy to give, yourself.  You can go to a feed store and buy the serums and syringe set ups, and the salespeople there can tell you if the shot goes into the neck or the flank.  They also cost much, much less this way.

I heard they need to be about 3 to 4 months old~

Yes puppies do need their shots. The should have their first one at 3 months old and their second one a few months after.

Yes, when they are 7 weeks old.

Yes, puppies need their shots. We went through a very bad case of parvo virus here in my area. My family and I raise dogs and we had 14 that died from parvo virus. It was very heartbreaking. Each and every one of them had their shots, but they weren't given soon enough. You should start giving puppies the parvo virus shot early. My vet normally says between the 5th and 6th week after birth and it goes in a series. They are required to have more than just one shot when they are puppies. Definitely check with a vet and they will determine what is best for your puppies needs.