Wow, I am a little overwhelmed reading your posts. Sounds like you are totally consumed by your Pom, and I just hope that your Yorkie will be able to stand up to the standards you have set for him because of your Pom.
Time flies by and I'm sure your breeder never meant to lie to you about his age. She did tell you he was not potty trained, which is more typical of Yorkies than not. If I understand correctly his teeth sound normal, and the extra teeth should be removed when you neuter him. Patience, Love and consistency is the key.
Your Pom is trying to show dominance by humping your Yorkie's head. They will work it out by themselves in 2-3 weeks, if given opportunity.
He may need wormed since he is so hungry. You also have another Dog there which if your Pom is showing dominance, he may think he has to hurry, although you feed them separately.
Make play time fun, and always give lots of hugs and kisses. You will be amazed at how great he becomes, and you wouldn't be able to imagine life without him. I always tell my families that it will take about 2 weeks to settle in even if there isn't another dog. Warning however.. once you own a Yorkie.. you can't have just one
I am looking forward to your posts of just how great this little guy is, how much you love him, and how much he loves you, and not so upset about what he isn't or what he is doing wrong!!
I am attaching a picture of 2 Yorkies that I sold to a lady at separate times, who fought for 2 1/2 weeks when the 2nd one came. It will work out!!