Welcome to YT. The standard for the Yorkshire Terrier is 5 to 7 lbs. You can find Yorkies in all sizes, very very small (never a good idea), to quite large. If your pup is a pet, the size doesn't really matter. For show, he would be too large. He's also too large for breeding. It sounds like your pup is going to be the size of a Silky Terrier.
As to the vomiting, your baby may be over eating. Be careful not to feed too many treats. If he is eating his regular food and everyone in the family is feeding him treats, his tummy may be too full.
As for the ears, the top third of each ear should be shaved. Taking the weight of the hair off may help the ears to stand. Sometimes it just takes time for the ears to stand, and other times they remain floppy. Take him to a good groomer and they can shave the ears if you are unfamiliar with grooming.
I highly recommend this website: yorkiepassion.com
There are many links there that have lots of information on Yorkies. Enjoy your baby. I have had Yorkies for years, and I get so much pleasure from our two babies, that I just love them to death.
