hey tpwelie34,
I think the first thing you should do is get fitted. Meaning, find out your measurements (suit and dress shirt). You can go to any Men's Suit department in any store and ask them to take your measurements. They'll find out your collar and arm length. Also, they'll find the suit that fits your chest. For example, in dress shirts I'm a 16 (collar) 34/35 (arm length) and my suit size is 44R (chest size and jacket arm length).
After you get these measurements, you can go ahead and try on different suits and dress shirts with the same numbers. Generally, you can try on any brand with the same measurements, but I tend to find that they all fit slightly different. So once you find a suit that looks good to you, I would recommend trying it on before purchasing it.
As for prices, the suits range in prices from inexpensive to really expensive. Know what your budget is before going into the store - the salesperson may try to push a high end suit.
Also, tell the salesperson that you're going for an interview. I recently bought mine and when I told the salesperson about interviews, he agreed on my choice. It's nice to have some reassurance if you go by yourself.
As for style, there's lots of it. Single, or double breasted. The number of jacket buttons. Type of lapel. Type of vents. I'd keep it simple with the basics first (measurements, color, fit, and price). You can get into details once you feel comfortable with the rest.
Above all else, you can go the custom suit route. But be forewarned, unless you go to China or some other country, custom suits will be expensive. You can go ahead and get priced, but it probably will be more expensive than a store bought suit. In addition, since you are new to this, getting everything custom may not be the best idea, because you should know exactly want in your suit and you haven't developed your style yet. One more thing, even if you buy a suit, you might need to make some alterations, so tack on another $20-$30 to your price tag.
I found this on wikipedia that gives a description of the suit anatomy.
http://en.wikipedia.org/wiki/Suit_(clothing)
Good luck shopping. PM if you have any other questions.