>>Can a lightsaber heat a rock in winter to keep you warm?
Yes! But who needs to do that, just turn the sucker on, insta-warmth!
>>Can a lightsaber be set on stun to incapacitate and not kill?
Doesn't need to. Chop off the enemy's arms and legs. insta-incapacitation! Because it's so hot, it'll seal the wounds immediately, preventing the loss of blood. And it can perform surgery.
>>Can a lightsaber fit in your shirt pocket disguised as a complex >>pager/phone?
No... turn it off and place it in your underwear to impress the ladies.