As Rocketeer said, the basswood strips is on the money for side strips. For the uprights you could do thicker strips or get some dowels. For a rustic fence I would take to them with some sort of knife or dremel and just hack away.
If the fence has been there a while and not maintained, I would substitute the brown wash for a gray paint and then a lighter gray dry brush to bring out the "hacked" up part.
For a beaten up roadway I would pour out a thin layer of Hydrocal or Plaster of Paris, and then after it's dry, break it into chunks. Then put the chunks back together on your dio base. Sand representling pebbles and bits of grass flock can stick out of the gaps in the road.
For puddles there are tons of products out there that you can fill holes and grooves with. HTH and I'd like to see how it goes.
