What kind of Vine snakes do you have? There many kinds of snakes that go by that name. Most typically there are the oriental vine snakes (Ahaetulla sp.) and the Mexican vine snakes (Oxybelis sp.)
For those the care is similar accept the Oxybelis will eat mice.
1. how often do they need to be fed -Once a week at least, I perfer to keep a few anoles running around all the time. Over eating is not likely to be a problem.
2. will they drink from standing water or does it need to be moving?...i was planning on putting a small waterfall in the tank. -They will drink from standing water, although moving water is prefered and will add more humidity to the air, another mportant husbandtry requirement.
3. how many can be comfortably kept in a moderately planted, 45 gallon hex tank? -None. Personally I think 45 gallons is two small. you need room for live ficus trees etc. I keep pairs in cages that are 260 gallon minimum.
4. what is the best substrate to use??...i was going to use peat moss to help with the humidity requirments. Peat moss, or soil are good they don't often come down to ground anyway.
5. as far as anoles...do you keep them for a few days and gutload them or just feed them out as soon as you get them...also, do they need to be dusted?? - I keep a cage filled with anoles since they are cheaper to buy in 50 or 100 lots. I feed them gutloaded mealworms and silkworms which are easy to raise.
I hope this helps. If you are interested in the oriental vine snakes I suggest that you find a dealer that you can get your anoles or Gecko's from cheap. Having a good supply of food is the most important thing. Most people who fail with these snakes do so because they under feed, or try to get them to eat other things.