This is not wordpress related question but I will answer it without any special reason.
First of all… all pages from old website are indexed on google and those indexed pages can not be deindexed at the same moment when you change the website. That is the reason why all pages show on google… so you have to wait or you have to play around in Google webmaster tools in order to speed up that process.
You can create redirections simply with this plugin:
http://wordpress.org/plugins/simple-redirect/
I hope that this will help you to understand what is going on.
But… as experienced SEM guru I would never combine all those pages into one page because of many reasons…. but that is not important now.