i dunno about the rest, but you got the first two completely and totally WRONG.
How is Halle Berry a bad choice? I think the artwork for Treir defies the writing. They describe her as this incredibly beautiful green sex goddess, and then the cover on the gamma books is this ridiculously ugly woman... Halle Berry? Now that works for me because she has the seduction act DOWN.
"The Rock" as Akaar is certainly open to debate, but with proper makeup he'd command that role pretty well. When he was first being described (both physically and in mannerisms) I immediately thought of The Rock.