dlsavvy,

Don't know much about world-wide taxation of US citizens, except you better see a specialist. Since this is a US pecularity, your best sources will be in the US - try the Fools Tax boards

With regard to transferring assets, I'm not sure what advantages you had in mind for a Swiss bank account and whether you are after local assets (many are purchasable on US exchanges) or want local bank accounts, brokerage a/c's etc.

If the later, try talking to HSBC - they have branches in Aust and NZ and may be the easiest route. There are always online brokerages (check their T&C to see if overseas residents are eligible).
Also have a quick look at the Australia and NZ dual tax agreements - you can usually apply to have lower rates of withholding for non-residents (both for interest and dividends).

Hope this helps - reply with more specific information as to what your needs ar and I'll try to answer your questions.

Regards,

Peter