I'll do my best to answer your questions. Though, not quite in order .

When it comes to where to store your configuration information, that all depends on the level of customization you want to give to the user. While its true that a script offers more flexibility, it also bloats the application and makes the configuration more complex. To this, simpler is typically better. Think XML or INI as your root configuration manager. Keep a recording of scripts, times, and run instances that need to occur some place outside of the scripting environment.

That being said, you can also have a global script instance that modifies your current run state. Make sure that this is optional, as many users arn't going to need this functionality.

For individual task scripts, think of it this way. You will need to initialize an instance of Lua for each separate task that you want to run where anything from another script should not affect it. If your using my TLuaObject and TLua objects, then simply fire up a new instance of TLua for each script that you want to execute. Then release that instance and clean up after yourself when the execution is complete. If you want config options from your root script to affect other scripts that run in separate TLua instances then you will have to manually migrate them. That can be a bit tricky, but it can be done .

Something to keep in mind is that Lua maintains state information until you call close. So if you run "a = 5" and then run "print(a)" you will get an output of 5, unless you called close between the two calls. Use this to your advantage.

Looking at: SDL, Lua and FPC game engine sample should be of some use. Also join the Lua Mailing List. Finally take a look at: My version of LuaTut and Lua FPC/Delphi wrappers, that has an updated version of LuaObject and LuaWrapper. New bug fixes that arn't in production yet, and some other fun stuff that will be presented in the book when its released.

Once you get your basic test bed working, feel free to post it up here with questions. I'll be happy to follow up and answer everything that I can.

Oh yeah, final note, PIL and PIL 2 are your friends. Read them, and buy a copy if you can afford it.