OK. So...first the basics.
You don't need a heating pad. A heating pad/light isn't necessary and could even be harmful to your tarantula. Just get rid of it. They will do just fine in anything from 60 degrees F to almost 100 degrees F. Warmer is generally better than cooler, but anything in the 70 - 80 range should be fine.
Don't worry about humidity with these guys. If it has a full water dish (which should be about the same size as the tarantulas leg span, AND NO SPONGE, adding a rock that overhangs the water level isn't a bad idea either), it's fine on humidity.
Tarantulas are the "Ron Popeil Set and Forget It Oven" of pets practically. All you need to do is set it up with some substrate (I prefer cocofiber, but vermiculite or untreated potting soil is also OK), put something for a hide in there, a water dish, and check up on it every once in awhile to feed it and see what weird "spider things" its doing, and they're fine.
Here is some information for a beginner and more specifically on G. Roseas. From one of the best sources you can find.
Care And Husbandry of the Chilean Rose Tarantula
Also, as an added bonus (In true Ron Popeil fashion) HERE is a great book to get you up to speed (authored by the person that authored all of those links I just sent).
One thing I'll add about the book however, is that it is a few years old, and therefor, some of the information in it is a bit out of date. Tarantula keeping is still pretty much in its infancy and we're all still learning/debating on what the "best" ways to keep these guys are. Take EVERYTHING you read, learn, hear, believe with a grain of salt. Always ask questions, and take the experiences of others to heart, but always be skeptical.
One thing I always like to mention because as new keepers, we get anxious over the little things:
If your tarantula is doing something "weird" and doesn't seem to be hurting itself, just take a deep breath and repeat "The spider knows how to be a spider better than I do" over and over.
Good luck, and welcome to the club! =P