The script info is a configuration setup for a module called mzscript.dll, which allows you to do a certain amount of scripting for LS as well as create customized bangs. If all you want to do is execute several bangs, you can also use !Execute, e.g. "!Execute [!SystrayHide][!TaskbarHide]" etc, for the number of modules you need to hide. That would actually be the preferrable way if you're not currently using mzscript.dll anyway.

As for the last question you asked, desktop2 and taskbar3 are not comparable modules. Desktop2 has no gui components whatsoever. If you're seeing something that does have some sort of GUI that's staying on top, it's some other module.