1: Could you make lava solidify into obsidian on cold bodies (like Eropa, Mars, and Pluto) and water evaporate on hot bodies (like Io, Venus, and Mercury)?
2: could you have something similar to the moon lander for Venus (due to the high pressure I don't think that a bunch of Cotten balls would be able to keep its shape, let alone be able to catch your fall). You could also add a special Venusian rover made of a stronger metal to be able to stand up. (The normal rover wouldn't be able to be placed)
3: along with the water evaporating and the lava solidifying you should add a heat controlled room where if you have a full room made of them then you could have liquid water and normal lava.