Wow! That is a young one and you have your hands full.
The breeders here at YT will be able to give you more information I'm sure. Some even tube feed, but I hear my breeder friends talk about feeding every two hours - no sleep and no life. But I know many tube feed.
There is also a puppy starter mousse for baby pups.
Yorkiemom1 hopefully will come and tell you more about all this.
Praying all goes well. I think you are great for taking this pup on