newbie to police scanning?

[implicitProdigy]

Okay I'm about to buy a police scanner (radio scanner)... And I neeed to know what is a good one to buy currently... I heard Radioshack has good ones. I'm trying to listen in to frequencies around Lake Charles, LA. Is radioreference.com a good source, also do codes change??? Or do they stay the same. If so, how often do they change. And what kind of Scanner am I going to need to listen into Police, ambulance, etc. What is a good started police scanner that doesnt drain batteries??? And please lemme know anything you think a newbie to police scanning needs to know