Welcome to YorkieTalk (aka YT). You're an

for adopting an older/adult dog. The youngest we ever adopted was Zeke at around a year old and Harley was around 12 (still intact, BYB S. GA?)
If there is a PetSupermarket near you, you can give them a try. What to feed your "pup". I would suggest doing a YT search on "what do you feed your yorkie" or something like that. Read the labels carefully or go to the company's website and look at the lists of ingredients. I/we try to give our pups the best possible but it all boils down to what can you afford. A 5 lb bag may cost $10-15 but these are smaller dogs and that amount will last longer as your pup should digest more of the food. I have links to another "Pet" site that also talks about pet food ingredients. PM me if you would like them.
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Zack, Zeke, Zoey, Zipp RIP 6/28/12