How funny, I just rescued a 1 year old "giant" yorkie as well. You can see him in my avatar or in my albums I think...I need to update some pictures but he is the one shaved down. His previous owner's didn't really care for him they way a yorkie needs to be cared for. Just remember, daily grooming as in brush hair, clean under the eyes if needed, and clean those teeth, if you don't keep his "member" saved down give it a cleaning as well with a dog bath wipe at the end of the day to keep that clean and free of any infection. You also may need to clean poo off from time to time, but keeping them in a sanitary trim will minimize this occurance. Like other posters have said feeding them a great food will keep them healthy which will make them happy. The best food that I've found that can actually be shipped to me is Wellness Small Breed which you can find at PetSmart and both of my pups gobble it right up. I sometimes add half a package of Ceaser to each of their dinners as an extra treat
Good luck with adjusting yourself and this wonderful pup to your home, he is so lucky to have found his way to you and your family.