The simplest answer is it depends on the rain, but if we assume that the rain is falling constantly and is falling straight down and you don't change shape as you walk, you will get wetter if you walk.

This is because the rain can hit you in two ways, it can hit all your horizontal surfaces by just falling on them, or it can hit your front by you walking into it. If there is no wind, the amount of rain that hits you on the front is just dependent on the amount of space you walk though, so how far you walk. If we assume that this is a constant the only thing that will change is the amount of rain that actually falls on your horizontal surfaces which is just dependent on how long you are in the rain for, so running probably does make sense.

Of course in the real world everything is a bit more complex, if there is a wind moving with you it may pay to move a little slower as you can get to where you are going without walking though any rain, just have it fall on your head by walking at the same speed as the wind.

Also if you are in a very short thunder shower that will finish quickly it may pay to move slowly during the shower as you won't run into any rain while it is at it's heaviest.

Although I still think in general running is your best strategy, unless you trip up and twist your ankle...

I guess the cast iron pot had a cast iron lid as well.  Microwaves cause electric currents to flow through metal, so you would get a current flowing through both the pot and the lid.  If the pot and the lid were insulated from each other, and there was enough voltage, you would get a spark as the current jumped between the pot and the lid.  This would explain the flash, and it may have damaged the enamel on the surface.  The spark is incredibly hot, and so this could have vapourized some of the enamel, which may be the cause of the smell.

It's unlikely that cookware manufacturers use anything too toxic in the enamel, as you may scrub bits loose and they could wind up in the food.  So although there may have been some enamel in the food, it should be relatively safe and in such tiny quantities that the food would not have been dangerous.

I think that trackpads on laptops work by having two sets of wires, one running horizontally and one vertically, and they they look at the capacitance between the two of them - so if you make a voltage with one of them, how much is that voltage picked up by the other one.  If you put your finger near it, this changes quite considerably, in fact if you put anything conductive near it it will change.  The problem is that if you've got thick, dry, calloused skin on the tip of your finger, this acts as an insulator and stops this effect from happening.  The ipod click wheel is either more sensitive, or possibly pressure sensitive.

As you age, your skin tends to get thinner, so it's unlikely to be the same effect as with the guitar string callouses.  In fact, thinner skin should be picked up more easily by the trackpad system.  Obviously, it depend on your life history - maybe your mature friend is a thrash metal guitarist?