There are three additional scripts in the Terrain Tools package that you might find useful.

Terrain/PlaceSelectionOnTerrain

This will simply lower/raise the currently selected editor object so that its origin sits square on the terrain. Very useful to place stuff on your terrain. Can have multiple game objects selected.

Scripts/SpawnInArea

This allows you to add yet another procedurally generated element. This script will take a spawnmap and spawn/position something randomly inside that spawnmap on your terrain.

I use this to generate maps that exclude the corners of the map, the very edge, and anything where the steepness of the terrain is too high. On maps with water, you can also use spawnmaps to make sure that the player (or objects, etc.) isn't spawned over/in water.

Scripts/TerrainQualitySettings

A simple script that will change the terrain quality in response to the game's quality settings. You should check and modify the values included depending on your particular game, and you need to integrate this into your game so that it is attached to a game object but also called whenever the quality settings are changed.

Scripts/TreeExplosion

A simple script I released before on the Unity forums. It shows how you can access individual trees, for example if you want to make your forests destructable. It's simple, but really nifty.