Engine push start button

[Muzz]

Hey guys, im interested in mounting an engine push start button in my car, however im concerned with security.

This is what im looking at - http://cgi.ebay.com.au/ws/eBayISAPI....tchlink:top:au

With it installed, you turn your keys on, and then push to start up.

I want to know:
1. Will this make my car easier to steal without the keys?
2. Is my immobiliser still effective?
3. if you pressed the starter, without the keys, would the starter motor try start the engine?
4.Will it make it easy to hotwire my car in any way?

What are your thoughts, im clueless when it comes to electronics