Sorry cyberkitty,
I know for a fact that SIA have employed caucasian crew (well at least 1 anyway), I have met her going through immigration. We were so suprised at this sight as we thought SIA only employed Singaporean and Malay also. After consulting some SIA crew I know I found out that she is infact caucasian but is also a Singaporean citizen, and stunning might I add!! I think she may be the only one though.
And yes, the males are confined to the galley positions. You couldn't possibly allow the girls to work in a galley with those open flip flops they wear (or do they change inflight).