1) colorful writing instruments. do markers dry out immediately due to low humidity?
I had a marker thingy last year. No, they do not dry immediately, if you just dutifully close the cap (is that the correct word?) every time you put one down. They do
get terribly clogged with the dust, though. I lasted for about three days before I gave up. It was impossible to keep the surfaces I wanted to draw on dust-free enough to have the pens working for longer than a couple of minutes at a time. I would suggest some other pen type, but if you settle for markers, be prepared to unclog them (water works ok) often, and bring extras.
EDITed to add: Maybe if you were in Center Camp or somewhere very closed to winds, the problem might be smaller. But I kind of doubt it.