Welcome to the forum.

You should check out the post below yours (ball python and cold apartment thread) They answer your exact questions.

Also, check out this DIY it will also answer most of your questions.

http://ball-pythons.net/forums/showthread.php?t=201740

Best way to keep heat and humidity in, is to close off most of the top of the enclosure (I take it you have a glass one).

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