> "Is there a tutorial available on learning Vegas Scripting?"
Afaik, no :(
> "Is Vegas Scripting simply Java Script with some additional syntax for Vegas?"
No. Vegas scripting API is based on Microsoft .NET, so you can write scripts on JavaScript .NET, C#, VB.NET etc.
You can write extensions on any .NET language
> "Is there an Development Kit for Vegas Scripting or will a simple text editor work just fine?"
DevKits here: http://www.sonycreativesoftware.com/download/devkits
In general, you can write scripts in any text editor (eg., in Notepad), but it will be much more productive if you use Microsoft Visual Studio.
You can get Visual Studio 2013 community edition for free. Has build in templates for javascript and typescript. Plenty of free resources on the net for javascript itself. It's gotten very powerful the last couple of years. If that seems a bit overwhelming for you, a very good text editor calle notepad++ is free and has built in language support for many languages, including javascript.