You don't "suck" at all, every new owner has to tweak a bit so no worries.

Basics here......
where did you get this snake?
what was it eating as far as prey type and size just prior to you purchasing it?
exactly how long have you had this snake and how often are you offering food?
what type of prey and the feeding method (rat or mice, size of prey and are you doing live, frozen/thawed or pre-killed)?
where is the snake's enclosure located in your home?
is the heat pad controlled by any kind of thermostat (you indicated it was but then it should not be dropping with room temps so just checking)?

Having some more info will likely help us help you better.

As far as your housing choices the 20 could work if you busy it up a bit more to use up the open space. Another hide midway perhaps, using a natural substrate rather than the reptile carpet (which you'll likely find is a bear to keep clean). If your snake coiled up is significantly smaller than the hide you can easily make some "baby" hides from any dark colored plastic bowl from the dollar store (usually 3 for a buck and smaller than a regular cereal bowl). You just melt or cut an entrance hole and you are good to go. Here's an example....

*note how smooshed in the snake is - bp's like this*

Anything you put in with a snake think easy to clean because they will drop urates and feces on anything and chipping off a dried urate or poop from some fancy bit of "cage furniture" loses it's charm pretty fast LOL.

As far as your original question about handling - no worries. Get your enclosure tweaking done, get the snake eating regularily, get it used to a simple routine of housekeeping/feeding and it will be getting to know you that way. As you work around it, feed it, etc. and establish simple routines it will come to see you as just a big heat emitting thing that doesn't particularily want to eat it. That's the first step.