For Maximum Growth:
I'd be inclined to improve the Corn before Wheat for the extra +1F. It may not seem like much, but there's a lot of growing to do to get to 5P, which is the limit of the happiness Cap, until the improved has a Route (6P).
It's hard to beat the strategy of increasing Population to the Happiness Cap at maximum speed. Growing faster with more Citizens working more tiles sooner usually beats growing slower with fewer Citizens working the best tiles.
For Earliest Possible Alphabet:
If the goal is getting to Alphabet fastest, then skip Agriculture. Research Hunting -> Animal Husbandry -> Writing, build Library -> Alphabet.
Alternatively, an Alphabet sling shot (via The Oracle) may make sense, especially with Masonry and connected Marble. It probably makes more sense to use the The Oracle to get a harder to research and more useful Technology like Metal Casting or even Civil Service (which may be hard to do on Deity).
For Alphabet sling shot, the Technology path becomes: Mysticism -> Polytheism -> Priesthood, The Oracle (Alphabet) -> Writing
Victory Condition choice:
After I learned to play Civ4 reasonably well, I've never started a game without having already being committed to achieving a specific Victory Condition.
It is especially not a good idea to start a Deity game without having a single Victory Condition in mind and a good strategy for achieving it.
Barbarians:
I would advise against selecting Barbarians for almost any Deity game.
Wonders:
Stonehenge is usually useful to have with any leader that lacks the Creative attribute.
As
WastinTime mentioned, The Parthenon would be a good choice for +50% GPP, especially with Marble.
For increased happiness (+3

) in the top five Cities and Research bonus (+3

) for Specialists, The Pyramids are hard to beat.
Stonehenge is reasonable to build without Stone, but building The Pyramids without Stone is questionable at best. It may be easier to allow an AI to build it and later conquer it.
For Deity, one generally wants to build only 1-3 Wonders that are key to a specific strategy and that goes back to the choice of Victory Goal.
Sun Tzu Wu