[gohm]

I was thinking treads for locomotion as well. Oversized so it can still run if it gets flipped over.

What about a gas detector? Can detect the threat of carbon monoxide, natural gas leaks, etc. that could be a risk to people entering area afterwards (scientists, rescue workers). The vehicle itself would need to be spark proof.

temp. probe or camera using IR.

A bulldozer type front blade to push objects out of the way to the side? That way you only need one grab arm. Arms would be more likely to break in a fall or tight places.

Do you want a speaker/mic/sound card for basic speech communication?

What degree of water resistance would this require? none, resistant or proof? I would vote for resistant.