I agree with Kevin.
Also, I highly recommend "Ratio" by Michael Ruhlman. Part 2 of that book is about stocks (broths)...and has an excellent section on vegetable stocks. (There is a technical difference between broths and stocks, but I don't think it matters in this case.)
Stocks are great! Stocks can make the difference between a great meal and a merely good meal.
"Can parts of vegetables that would otherwise be discarded be included (eg. potato peel, carrot tops, onion skins)?"
Yes, as long as they are clean and fresh. Personally I'm not fond of adding potato peels.