Hi - I know what you mean about the blind leading the blind! I have so many questions too, all the time! But I'll answer your questions as it applies to my Charlie.

Charlie doesn't have bottles often (the last one was probably about 3 months ago), but when I do use them I still sterilise them because they have more books and crannies that could get bugs in them. He doesn't have dummies, but I don't sterilise the cups he drinks out of. If you were really concerned though, you could compromise by leaving cups, dummies, etc. in a bowl of freshly boiled water from the kettle for a few minutes. I also give Charlie water, but I just boil it in the kettle about half an hour before he needs it and pour it into his cup to cool.

Charlie has been sleeping on his tummy since he was 6 months old. I was really stressed to begin with, but he knew how to roll over, and no matter how many times I turned him over he would just go back onto his tum again, so I didn't see the point!

Can't say about the milk thing - C is breastfed and is a bit younger than Mackenzie (love the name, btw!). Hope you find some answers that suit you.