He can't turn into a lamp mechanically, he can just look like the lamp in a fashion similar to a cuttlefish looking like a hunk of coral. The cuttle fish is still a cuttlefish. Ergo, Claymoor would look like the lamp, but the lamp would be squishy and unable to function as a lamp once plugged in. He can't turn into anything, rather he can imitate it superficially as he's basically a sentient gellball. The telepathy wouldn't affect other characters, rather it would allow him to think like we would as his brain matter is spread out throughout his body with no physical connection. It's like cable versus wi-fi. As for him being a killing machine, er... No. He's composed of cell jelly. The cell jelly does not stop being jelly when it imitates metal. The consistency and make up is the same. The only thing that's changed is the color and texture externally. The worst he could do is stick to your hand and try and digest it, which wouldn't work to well because you could scrape it off before it has a chance to do anything.

He couldn't turn into a space ship, nor gas, because that would be impossible. It would require him to alter what he's made of, which like every other creature out there, is cells. Cells cannot turn into gas, a gun, a ship, metal or anything at all because that would be rediculous. They can however rearrange their configuration to look like something they're not, but that's all they'd be able to do, look like it. Not functionally become it because that would require him to cease to be composed of cells.

As for the car thing, he wouldn't literally become a car, he'd just look like one (he'd need to take wheels, axles and a few other parts from an existing car to even imitate it in the first place) but the imitation car would not be able to go as  fast as a real car and if it ran into anything it would splat like a stick of butter because it's made of cells.