Dear Pmarple

Laterite  bricks or blocks are made from laterite stone generally found in southern part of  India. It is soft when wet but on exposure to air it gradually hardens as the moisture between the flat clay particles evaporates and the larger iron salt lock in to rigid laterite structure and become resistant to atmospheric conditions. Nearly all laterites are rusty-red because of iron oxides.

In my view, As stated by you that brunt bricks are not cost effective. Use FIRST CLASS BRUNT BRICKS which have crushing strength more than 105 kg per cm sq and observe water more than 10% after emersion in water for 24 hours. Brunt bricks if laid with proper bond, joint at corner and have good bond with plaster are better than other. The concrete block is cost effective, not give good bond at joints and have no good finish with plaster. The laterite bricks also have same problem and plaster may be weak after some time. Brunt bricks also space saving.

Dear Pmarple

         Use cement concrete block, for windows frame use hard wood as cost saving or use iron window frame. Painting have more life than polish. polish surface become weak on rain water, sun, heat and cold.