Creepers spawn any time of day or night, whether above ground or underground. They can be very annoying, especially if you are working on a project that gets blown to pieces in the blink of an eye by a creeper. You can take actions to protect yourself though. Surround your house with cacti (or lava, if you prefer that). Dig a trench around your house, so when they try to come at you, they simply fall in a hole. Or build your house out of something that takes less damage, like smooth stone, stone brick, clay brick, or obsidian (even if obsidian is incredibly ugly).
As for learning how to craft, there's not really any "easy" way to do it. The Xbox version of Minecraft has a full list of all craftable items, but the PC version relies more on the user to find that stuff out for himself or herself. I would say your best bet is to just compile a list of items and their recipes. Try this web page (not sure how up to date it is with the latest version of Minecraft):
http://minecraft.ign.com/crafting-recipes
Save that page so you can still access it when you are offline. I'm not sure if it has ALL the recipes, but it has a great deal of them.
@Additional Details
If you are looking to learn without the Wiki, you are in for a rough time. It's not that it's impossible. Plenty of people have done it (the Wiki didn't exist early on in Alpha). But the Wiki was created simply because figuring out the recipes by trial and error takes a LONG time, more time than it is usually worth. And while most recipes are fairly straightforward (like making a fishing rod by creating the shape of a fishing rod out of sticks and string), some are less intuitive. For example, if it weren't for the Wiki, I would never have figured out how to craft a jukebox, a note block, or even a painting! They are weird combinations of items that, in my mind, are almost impossible to figure out without simple guessing (let alone items that you don't even know exist).