question 1) -- 1.4.3 is specific for jboss AS 5, usually we don't provide a download. But you can have this version at svn:
question 2) -- 1.4.3.GA has been tested specifically against remoting 2.5 in order to be released for AS5.
If you are using 1.4.3.GA, stay AS5 and remoting 2.5. It's not guaranteed that 1.4.3.GA work with 2.2.x remoting.
We don't provide a download of 1.4.3.GA because it is compiled against the libraries for JBoss AS 5.0 only.
It won't run in EAP or AS 4.x.
Since it's already available as part of JBoss AS 5.0, there's no need to provide a separate download, it's already pre-installed.
Thank you for explanations, I'm glad to see that jbm1.4.x is now compatible and tested against jbrem2.5.x