Er, from what I read, there's quite a bit of variation between enclosures. You can have the natural look, or the more bare-bones, but simpler to care for.
If you don't really care how it looks, just use paper towel as a bottom, as it's the easiest and cheapest way. I'm not sure of hides, but I don't know....a small bucket? You'd have to ask someone else for that. Apparently, a small margarine container works as a water bowl, but you may be better off just getting a cheap ceramic bowl that's not tippy.
If you go for the natural look, repti-bark is okay, but aspen is easier to care for. Live plants for a 4.5 foot snake will probably break rather quickly, so plastic plants would be best. I have no idea what kind of hide a larger snake needs, since I'm using little coco-huts at the moment. You can get water bowls that look like rock, which is what I have. A few branches and such should be fine, as long as you boil/bake them to kill everything.
Now, for placement, two hides is best. You can put one on the warm side and one on the cool side. The water bowl should be put on the cool side. For what I've seen so far, try to make the amount of 'hiding space' about the same on each side. My warm side was totally bare except for the hide a little while ago, and he refused to go near it. My cool side has live plants and such in it, so he seems to prefer that side much more.
Remember, the best temperature on the warm side is 80-85. Both heat pads and heat lamps do this fine, but some heat pads get too hot. I had the Exo-Terra 'Heat Wave', and it was going into the 100s. To make sure you know the temp., have two little stick-on thermometers, one on each side. I believe one inch above the substrate is what i've heard.
I have a pic f my enclosure in this forum somewhere, and apparently it's okay.