Firemen wear their Long Distance medal (and presumably any others they are entitled to) as an enamel brooch on the working shirt. Clearly the normal ribbon would not stand up to a daily soaking.
I really don't think so - not in military uniform. Next step would be to cover the ribbons in clear plastic, as some republics do. Terribly outre, I'm afraid.
Given that the locals here are dressed up like, err, Christmas trees (if they had them, of course) I might go along with local British Army practise and wear ribbons on my shirt. Sadly the Bush Jacket is an obsolete piece of kit; I soooo wanted to dress like Roger Moore...