Install..update issues..!!

Hi,

I am trying to build an application for Series 60 3rd edition on Symbian OS version 9.1.

If I have installed this Symbian application on my Nokia E61, (something like a game) and want to update it over-the-air, what are steps to be followed?

Do I need to uninstall the original version of that application?

What are the ways in which I can send a notification from the server that a newer version is available?

How does the currently available applications send update notifications and how are those updates installed? Are there any free softwares like Nokia Software Updater which take care of updates for third-party applications?

I know the default installer come into picture if I send the sis file through the nokia pc suite...but does the installer work the same ways even in the scenario of OTA?

Cheers
mayank