> 1) What more do I need to do on the Linux side to make sure that
> Jaybird is up and running?

You need libjaybird21.so only if you want to connect to Firebird 2.1
alpha using new optimized wire protocol. If that is not the case, you
can use pure Java implementation, that is you need only
jaybird-full-2.1.1.jar in your classpath.

> 2) How do I structure the stored procedure call statement in the XML
> file -- that is, what is the syntax for calling a Firebird stored
> procedure with input and output parameters in XML?

Huh? Jaybird does not parse the XML files. However it supports the
escaped syntaxt, which is

{call my_proc ?, ?, ...}

or use normal SQL:

EXECUTE PROCEDURE my_proc(?, ?, ...)

> 3) Are there any simple test programs, either windows or linux, to
> test the JDBC driver and perhaps the XML calling file?

You can use DriverExample.java, only correct the path to the database to
which you want to connect.

Roman