Hi Suri ,
Great thought.Infact most of us have dust problem.Especially during summer dry season even if we close all door and windows ,somehow dust enters.
Here's my take

lastics and vinyl finishes can be cleaned with Colin.It dries quickly and safe to use.But Don't use too much all at once.Regular cleaning keeps things clean.
Vinyl finish speakers can benefit from automobile vinyl polish but use utmost caution.Don't try if your speakers are expensive.If you want to try first take a small drop in a clean cloth and apply at the rear side of the speaker and check.Again wipe off with a clean dry cloth.
Metal parts especially Speaker terminals, Interconnects etc can be cleaned with Brasso ( cost effective) or any other good metal polisher.
Transparent polythene cover is simple and cost effective.Better still is the thin thermocole sheet (the ones you get with LCD packaging).We can use it when ever our system or speakers are not in use for a long time.
Mostly ants and worst still termites cause havoc to speakers and equipments.
Most all purpose insecticide and cheap ant powder ( I don't know what to call it) that you can get anywhere works well to control insects.
Vacuum cleaner is also very helpful in cleaning cobwebs on ceiling , rear side of TV , AVR, speakers etc.
Caution keep chemicals and insecticide out of reach of childrens and always unplug equipments while cleaning.
Well that's it for now I'll try to comeup with more options.
PS:Suri I see a spiderman hangin on top left in one of the pics.

And what are those speakers.Looks like B&W nautilus to me.

Also you wiring needs serious tidying.
Cheers,
Sam