Thanks! Both approaches worked, i.e. I've loaded globals on Scene Load, but then I have to specify them as "var myVar1 = window.myGlobal" in every inside script. Persistent symbols' values worked too. It's a good way, if you want to keep project globals "visible".
Of course, they wouldn't work across documents. For that you'll need to implement such thing as "project" (as Flash did at the end, but it didn't save it..).