URL?

You should develop applications first
<http://www.physci.org/codes/javafaq.jsp#appfirst>

Which versions specifically?  Note that Sun also made
Java 1.1.8.  If your Applet uses things like BufferedImage
or Swing, it will not work in a Sun 1.1.8 VM.

Yes.  At least you can specify a minimum Java version
(you should not need to care who's compliant VM it is).

No.  You can use the nested <OBJECT>/<EMBED> element
for Java versioning, but I hava a better solution.

You can put the JavaVersionApplet in your page as well
and redirect Java 1.1 VM browsers to a different page.
<http://www.physci.org/codes/jre.jsp>

BTW - While x-posting is better than mulit-posting, it is
generally not wise to x-post between c.l.j.help and c.l.j.programmer,
as the nature of responses can be very different.

I will set the follow-ups for this post to c.l.j.help.

HTH

Not sure if I understand your question. You ask how to add required jar
file to a Netbeans project. Then you say that it works fine when you
test it under Netbeans. I take it you do not want to update your HTML to
make it run.

If so, under your Netbeans project just this It is a two step process.
One add library to Netbeans and then add that library to your project. I
run Netbeans 1.5 but this has not changed for some time.

External jar file just for project
1 - select your project, right click and select properties
2 - select libraries
3 - select Add jar\folder. Then add it and select OK

External jar file as a library that any project can us. After this is
done Netbeans will let you add the library to any project with out
having to make a reference for it's location

1 - select your project, right click and select properties
2 - select libraries
3 - select add new library and then Manage Libraries
4 - enter a symbolic name for the library
5 - your new library reference now hows in the library list
6 - select that library
7 - select Add jar\folder. Then add it and select OK
8 - The finally select OK.
9 - The external jar file is associated with a Netbeans library name. So
on any project you can just add this library.