Y'know, a lot of people talk about ASP.NET, but it's surprisingly hard to find a clear and coherent definition of exactly what it is and how it fits into the world of Web development. Fortunately, Wikipedia has a very nice definition:

"ASP.NET is a set of web development technologies marketed by Microsoft. Programmers can use it to build dynamic web sites, web applications and XML web services. It is part of Microsoft's .NET platform and is the successor to Microsoft's Active Server Pages technology."

The Wikipedia entry continues with:

"Even though ASP.NET takes its name from Microsoft's old web development technology, ASP (Active Server Pages), the two differ significantly. Microsoft has completely rebuilt ASP.NET, based on the CLR shared by all Microsoft .NET applications. Programmers can write ASP.NET code using any of the different programming languages supported by the .NET framework, usually (proprietary) Visual Basic.NET, JScript .NET, or (standardized) C#, but also including open-source languages such as Perl and Python. ASP.NET is faster because the entire web site is precompiled to one or a few dll files on a Web Server and the Web Site runs faster compared to the previous scripting technology.

"ASP.NET attempts to simplify developers' transition from Windows application development to web development by allowing them to build pages composed of controls similar to a Windows user interface. A web control, such as a button or label, functions in very much the same way as its Windows counterpart: code can assign its properties and respond to its events. Controls know how to render themselves: whereas Windows controls draw themselves to the screen, web controls produce segments of HTML which form part of the resulting page sent to the end-user's browser.

"ASP.NET encourages the programmer to develop applications using an event-driven GUI paradigm, rather than in the conventional web scripting fashion. The framework attempts to combine existing technologies such as JavaScript with internal components like "Viewstate" to bring persistent (inter-request) state to the inherently stateless web environment.

"ASP.NET uses the .NET Framework as an infrastructure. The .NET Framework offers a managed runtime environment (like Java), providing a virtual machine with JIT and a class library.

"The numerous .NET controls, classes and tools can cut down on development time by providing a rich set of features for common programming tasks. Data access provides one example, and comes tightly coupled with ASP.NET. A developer can make a page to display a list of records in a database, for example, significantly more readily using ASP.NET than with ASP."

Not enough data? There's also an official ASP.NET site that offers tons of information, downloads, developer tools, starter kits, and much more. Indeed, one of the more popular tools on this site is Visual Web Developer 2005.

In terms of your specific questions, it appears to me that the entire point of ASP.NET is that you don't have to learn JavaScript, CGI programming, or Cascading Style Sheets.

This isn't to say that you can't go into the ASP.NET code and tweak things, however. If you do know JavaScript or CSS, it certainly appears that you can fine-tune your code to make your site work exactly as desired.

In any case, I hope this answers your questions. In addition to the ASP.NET site, remember that there are also a range of ASP.NET books available too, if you prefer learning that way.