I have had my little Aussie for just a week now, he (or she) is about 5 months old. I am just wondering what I need to do to can him in A1 Health. Do I need to get him vaccinations? Any treatments for lice? Worms? Fleas?

I am very new at this, and I want to do the right thing.
Also, I have heard if they have too much Egg & Biscuit Mix, they can die? Is this true? What is the right amount to give them?
I have also heard that some foods are poisoness to them, what are some of these?