I don't mean to rain on the parade of anyone who's hoping to get some money out of NASA for this sort of thing, but these issues are not entirely unknown in the design of pretty much any mechanical or electronic system used on Earth. Unless Mars has some damn bizarre combinations of compounds on its surface, I don't see why most of the answers could not be found in existing literature.

Do you have any idea how much quartz sand is all over the planet? If quartz particles were going to kill people off, there wouldn't be anyone left in North Africa.

Will there be dust on Mars? Sure. Will it be a problem? It could be, but sand is a problem for military machinery in Iraq, too. It can be designed around.

As for radioactive particles on the surface, has anyone checked on Moon samples? The Moon sees even more radiation than Mars does.

I agree that if there were organisms, it would be extremely difficult to keep them from getting into the inside of any habitats*, and that a lot more work needs to be done with probes.

*Not impossible. I have a few ideas in this area.