Aliens are not real, there for this is un-answerable.
They don't need water
you use the water gun.
Yes you do but I'm not sure if you have to use warm or cold
NO
So far as is know there are no aliens.
to get rid of alens you need to use the raticator.if you have not yet bought the ratcave you can use a water gun.
you put them in warm water :)
you put them in warm water
The easiest way for space aliens to get water would be for them to mine it from an ice asteroid or moon. The "iceteroids" would not require hauling ice into space-- it is already floating around in space! See the link below to read about a story explaining this sort of thing.
flying saucer
The aliens need to use earth's satellites so that they can coordinate their invasion efforts.
In Cosmic Destruction, you already unlocked all the aliens. You need to choose them first then you can play as the selected aliens. For Bonus aliens to unlock, go into the cheat section and type in the codes, Primus and Classic to unlock Fourarms and Rath. However them and the given aliens (Swampfire, Humungosaur, Ultimate Echo Echo, Ultimate Spidermonkey, NRG, Water Hazard and etc) are the only aliens that are playable in the game.