Just a bit on the visor fist. Some I see are two layered motorcycle visors. The base layer and the cut out for the second raised layer. some people use sheet plastic for the second layer as it is a much more subtle look. its all personal preferance.
As far as the weathering there is a technique that plastic modelers use on model airplanes and such. A base layer of silver is put on then sealed with clear coat (again personal preferance. Some people use gloss and some use flat clear coats. gloss tends to be a bit more dureable for the sealer purpose. It may make the silver look too shiny compared to the final top color but just seal the whole proccess, final coleor, powders and washes included, with a final uniform clear coat.) after silver is sealed then rock salt is applied to surface that u want silver and then salt recieves a spray of water to moisten and partly melt salt together. all of the final colors are applied and dried. Then simply wipe off the salt. It will come off easily and will leave behind realistic paint chips. when paint chips it chips in random patterns and they tend to have sharp jagged edges. just a little fyi.. finescale modeler did an article a bit back and they may have it on their web site.
ZONKRE