[Admins]

Lua is much much simplier than languages like Graal Script, Flash etc., and is easier to optimize. However there are few things that make it not good for our use: the syntax is very different to C/C++/Java/JavaScript/Flash/Graal Script, and of course most Graal stuff is not existing or at least not in the extend we are using them (join/leave classes, sleep/waitfor, variable scope, dynamic allocation of variables, automatic event binding etc. etc.). So it's quite interesting, but not a drop-in replacement. If we ever switch to another language or system then only for speed (e.g. a just-in-time compiler which exist for all platforms, including iphone, llvm might be the light at the end of the tunnel) or for better compatibility with code from other platforms, including Flash and Java programs.

All variables are stored in hash tables yes.
"unknown_object"s are mainly GUI objects or so which don't have a name. They still exist in the global variable space though.