I love the idea of setting a battle map for the town and having the players and the GM facing off with the overgrowth, its a wonderful mechanic and should keep the adventure tense - it also really helps differentiate it.
I think a nice addition would be an optional hook for how to get players involved if they don't live in the town, maybe something like the 7 Samurai.
I like how you presented the monsters and their loot, which was a useful addition.