However, there may be some other differences with regards to syntax that will have to be changed
2. You will need to install another server to handle Java requests (JSPs and servlets) but most servers give you the option of using IIS as the external web server. JRun is pretty easy set to set up as a Java request handler, but I personally prefer Tomcat. Other popular web servers include, but are not limited to: iPlanet, Orion, Enhydra, Websphere, and Weblogic. I'm sure each provides their own mechanism of allowing IIS to be the front end.
3. JSPs are written using pure Java, so as long as it meets the API specification (currently it's 1.1, I believe), than any server with JSP 1.1 support should be able to use it. JSPs also allow you to create custom tags that can be made to conveniently perform common tasks. For example, you can make a custom tag to make a database connection and execute a query with the syntax being something like:
<ns:mytagclass query="insert yadda" />
I think you get the picture.
Also, once a JSP request is made, the compiled code is stored in memory, so successive requests are loaded with hardly any latency.
Of course, many web servers have plug-ins to support ASP, but until ASP 2.0 or ASP+ or whatever it's called emerges and matures, JSPs are the way to go! you can look at benchmarks at http://www.orionserver.com
to see how fast JSPs are compared to ASPs.