Looks pretty decent, I might get a chance to use it in the not too distant future, and if so I'll let you know how it went. Some random notes on reading through:
- there's no actual river on the map. I'm guessing Grass River is named for a creek or stream? Might be worth including it on the map, since it could be tactically important (maybe the PCs use some ruse to force battle at a crossing, giving them a tactical advantage).
- I don't think you're allowed to take 20 on Hide and Move Silently checks (page 8), since there's a penalty for failure (i.e. being noticed).
- you might want to include some notes on what happens if the PCs split up to deal with several factions at once - say, the Paladin goes off to talk to the cleric of the Sun God while the Bard is schmoozing with the elves. Some other weirdnesses that I could see coming up include the PCs lying to various factions until the battle's over, PCs using Charm Person to convince everybody to get along, etc.
- did I miss a town statblock? Seems like a good thing to include.
- historically, watermelons were cultivated in river valleys (originally the Nile), generally in relatively warm regions. Might be a useful tidbit for some additional colour.