hi
for the first question: dont know.
its not so much work to click that one combobox for target version, since you already have to open the project properties to add the away3d classpath.
for the second question:
in flashdevelop each variable need to be type-declared
var cube:CubeGeometry;
instead of var cube;
you get an error, because some where in your code you seamto declare the type of the cube again.
if you upload the whole code, i can fix it for you.
hope that helps