Basically your saying if I know or figure out how to integrate apache2 and tomcat7, I should be able to configure xammp and tomcat7 ?
As some would say "That is a Roger, Andy"
XAMPP's Apache is no different than the same 'minor version' Apache released through any of the various repositories. It uses the same sources, and works identically. What IS different is all the configuration files and the modules that are 'complied in' AKA hard-linked (that means the mod does not need to be added to a configuration file). The Apache core is identical. In a package installation, the setup tools read other configuration files (all of linux is based on text configuration files) in locations that are known to them. (and that is the big difference in distributions really). So, in the end its 'all configuration'.
As to how Tomcat 'knew' MySQL was there - Likely a call to port 3306 and possibly an installer that used a grep/regex to search for configuration files or mysql.sock. Was LAMPP already installed when you installed Tomcat??
As for Tomcat support, it's really a totally separate (as you learned or knew) application server. There's a fair amount of debate if XAMPP should include it in future releases. Its inclusion with the Windows version of XAMPP, is a by-product of team changes at XAMPP and the use of pre-compiled Windows binaries, so XAMPP for Linux was unaffected.and thus -- no Tomcat.
Its much like the matter of 'how much' do we support PHP or Perl questions -- at some point (once things work) -- those questions belong on a language/framework oriented forum or mailing list. Should we teach folks how to compile when needed? I spend a lot of time explaining the workings of Linux or how to use the command line...
The XAMPP forums are here to get things working, and to offer some insight into why things are the way they are.
Good Luck and thanks for the inquiry. I hope I helped clarify things.