Not necessarily. A patented design can be stolen, as you see from various third world manufacturers all the time. A patent in theory keeps your design from being copied or stolen, but more often than not just allows you to sue the people who did copy or steal it. It's not so much a protection anymore as it's a way of proving who did it first... or at least who registered it!
A patent takes time to research because there are literally millions of patents out there, and yours has to be significantly different from any other active patent, or else you can't have it. It takes lots of time to search through all of these things, especially since the patent office is government run. Also, patents run out after a period of time- the maximum I think is 50 years. After that, it's anyone's ball game, and if your patent application is similar to an existing one that will run out in a year or two, you might be able to get away with patent pending until the other one expires.
Def