Chris, welcome to YT. Mia is still very young and you have a lot of work to do but you will find most answers you need on the forum.
1. First and foremost take her to the vet. She will need her series of shots that should be starting now I would also suggest having her wormed. Also, the tick needs to be removed. take a pair of tweezers and pull it out. Stab it or cut it i half and flush it down the toilet. The vet will put a frontline on her neck and that will get rid of any further ticks that you may not see and eggs.
2. I recommend Natural Balance from Petco because it has great ingredients but she might be too small for the kibble right now. My breeder had Chewy on a puppy cereal at this age because he was so small he was also on Royal Canin puppy food until he was old enough to switch to NB. I'm not sure about milk, but I wouldn't do it
3. Regarding the supplies, you need a small crate, a comb - she will need to be brushed daily and some toys that she can safely chew on. Don't worry about giving her a bath at this point, she is just too small and will get cold very easily. Also, the most important thing you can get is the Nutrical. These dogs get low blood sugar and you can give her 1/2 inch from the tube 2-3 times a day. I suggest the book Yorkshire terriers for Dummies but any book will probably give you sound info.
get to the vet and they can help you as well, also your breeder should be able to answer health questions for you and give you the pups health records.
Good Luck!