I have used both LEDs and lamps and both can be used with good success.

Plastic has a shine that is not realistic when done as bricks or wood unless said bricks and wood have been painted with a high gloss paint.  Dullcote will take off the shine.  Another way of making those buildings look better is to fill the mortar lines in the brick or block, a light gray acrylic paint worked into the grooves and then cleaned off the surface will both dull the surface and color the space between to make the detail pop out. You can also fill the shadows and grooves of siding to give the same relief, but pick a  silmilar color in a darker shade.

Rolling hills and sandstones can be done without plaster.  Granites and other igneous rocks require sharper detail and plaster casting are the easyest method but if you are an artist you can carve the foam if you want to do the work.  A smooth surface painted, covered with ground cover,  bushes and trees and no plaster necessary to create a pastoural scene.