Do they need a heat light?
No, snakes fare much better in captivity if given a heat gradient with under tank heat. For this you need some sort of undertank heating pad (some people just use small human heating pads). Place the heating pad under one end of the tank so that there is a warm end and a cool end. It is a good idea to put a hidebox at each end of the cage as well.
The temp of the substrate at the cool end should be in the lower 70s and the high end in the mid 80s.
How larger do they get?
Adult pueblans are usually around 30-36 inches long.
are they friendly snakes or jumpy and bity and seem to never want to be handled.
Pueblans are very jumpy snakes when small and don't really appreciate being handled, as I am sure you have noticed. They eventually grow out of this, although it can take a while! Usually, by the time they are about half grown (1-2 years) they will calm down appreciably.
Also, be aware that all milksnakes are escape artists, and if you don't pay strict attention to securing the cage, it WILL escape and be very difficult to find.
also how often should i feed him?
I would recommend feeding a small meal (that barely leaves a noticeable lump) every 5 days or so.
How long after introducing her to her new tank can i handle her?
I would leave her alone for 24 hours or so before handling her. Also, don't handle her for 2 days after feeding.
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Chris Harrison
...he was beginning to realize he was the creature of a god that appreciated the discomfort of his worshippers - W. Somerset Maugham