Very complicated setup...can it be done?

I have been using CS Cart for several years now and have overcome most obstacles with it in terms of matching it to my business processes however all of that is about to change which I think will stretch CS Cart beyond its capabilities so I am asking for your help in how I could do the following.

I am in Australia and at the moment half of my suppliers will drop ship and the others will not forcing me to carry stock of their products. I use Australia Post for the stocked items and the drop ship suppliers use their own shipper with some not even charging shipping.

I only sell to Australian customers in AUD however all that is about to change.

Changes are about to happen:

  1. I have been made an agent for a US company who drop ships, uses USD and ships via UPS
  2. I will be selling products:
  • From Aust to Aust (as I do now)
  • From Aust to New Zealand
  • From US to US
  • From US to Aust
  • From US to New Zealand
  • From US to UK
  • From US to Sth Africa
  • From UK to UK
  • From Sth Africa to Sth Africa

    Problems I have are Currency, Shipping, Taxes, Duties and Product range.

    The Product range is not exactly the same in each country yet the customer can buy from several sources. For example an Aust customer can buy product ‘xyz’:
  • for $1 AUD from Aust to Aust using Aust Post shipping OR
  • he can pay 0.90c USD from US to Aust using UPS shipping

    on the other hand product ‘abc’ is only available to Aust from Aust

    With Taxes and Duties any item coming into say Australia from the US over $1,000 has GST applied so drop shipping from the US supplier to an Aust customer is difficult when the customer has already paid me for the order including GST or not. CS Cart has to also know about the GST in this instance. If it is sent to me then double shipping costs have to be applied which either eats into my margin or the customer gets the product direct instead of through me. - this is just an example of one of the complications.

    Any suggestions on what processes need to be applied and how CS Cart could be setup to assist in all this? For example am I better to have several CS Cart Installations in each currency to avoid exchange fluctuations and be made region specific etc etc etc.