How do those centipede looking bugs get into my house?

They can come in under the doors, they can chew holes in the walls, they can hide under furniture and under carpets and they can come in through cracks you missed. It's virtually impossible to bug proof your home. Honestly, some ants are kind of beneficial to your home because they'll come in, leave everything else alone, and basically clean out all the pests for you. Your best bet is to regularly take out your trash and keep your home clean, also you might want to consider laying out bits of poison all over the place if you don't have pets.