Hi Scott: A covered front porch serves two purposes: The practical purpose of protecting the porch dweller from rain and sun and secondly, to fit the architectual style of the house. I would start with the latter to ensure your finished product looks right. No sense in going through the time, hard work and expense of putting up a covered porch that looks terrible.....you'll just wind up taking it down. I'd suggest that if you don't feel comfortable designing it yourself, get a local residential architect to help you design it. I know this seems like an unnecessary expense but with the porch as you've described it, you'll be very glad you did.
Structurally, porch roofs are usually designed into the framing of the house and the post footings will have to be dug and poured.
This will not be a minor project. Unless you do this kind of construction occasionally, suggest you obtain the help of a local builder who does. It can be a bit tricky at times. :-)