Good luck.. the highest atmospheric density on Mars is equal to the density found 35 km above the Earth's surface
I think a latex balloon filled with hydrogen could achieve positive buoyancy. Just bring a little bit of water and you can make your own hydrogen.
I don't know of many latexes that are springy at -100 C.
Touché. See Camper Bob's response for something that would make more sense.
It wouldn't have to be latex. What's wrong with mylar?
There is, to a first approximation, no atmosphere on Mars. To a slightly better approximation, there is an atmosphere on Mars, but only enough to cause trouble, not enough to actually be useful for anything.