I'm pretty darn sure that you would have to render your scene file as a .bmp sequence in order to pause and save what you have so far and then resume rendering at a later time. I render animations on my laptop occasionally and haven't had a prob with overheating since I put the machine up on thin wood blocks(also acts as a cooling channel) and use a small fan to blow air from the side. This cools the laptop from above and below. I've rendered animations up to 15 sec. long with no signs of distress from the machine.