Is imessageonandroid.com really an iMessages app for Android or is it Scam? I saw on a website that they have an iMessages app that lets you text iPhone user for free just like it is for an iPhone user texting another iPhone user. 

Do you use our own number, or do you have to have an apple id and use your email like the ipod touch?. Also please explain me how it works and what you have to do?
The website is fraudulent. If you try to download the app, it gets you to "answer product surveys" (that is, it's a cost-per-action scam), and then installs software on your PC. If there even is an Android app at the end of it, it's almost certainly malware.

Think about it. Why would Apple give access to their closed chat system to some no-marks app that's not even on Google Play, when they don't give access to reputable software vendors? Why isn't there any corporate information (the name of the company, their address, or even the country they operate from) on the download page?