rock's always been alive in brazil and bands such as iron maiden, deep purple, wakeman and english rock ensemble, knoppfler, clapton (i think), dio, page and plant, satriani/vai/dream theater have visited often

rock in rio is one of THE rock festivals (imo = THE)

Australia i don't think has the appeal to most rock acts that south america has. Even when bands such as springsteen (the once), bon jovi etc have played there the tours tend to be kept very small... perhaps just 2 big cities

Silverchair i hated from the first listen from the rock in rio tv broadcast and i'm glad i've not had to see them open for UK rock shows

hellacopters yes, though i didn't know about stratovarius... but basically any bands like that (manowar, maiden, strat.) can play South America because their music is appealing to the rock culture there

BJ don't play Aus/S.A/Asia/Africa in my opinion because there sound is not as fitting for the culture anymore... certainly not enough to play stadiums