Hey Ian,
It's nice to hear that you are doing some customization, we will be happy to give you some tips to get you going in the right direction.
When you turn on multi currency, QB creates a new Accounts Receivable for that currency.
ie: Accounts Receivable - CAD would be for the Canadian currency.
Make sure that you are selecting the correct AR Account, I noticed that I was getting conflicts in Method because I had the wrong AR Account selected. You can automate this by customizing the Estimate screen with some extra actions. A tip is to look on the Customer Dropdown list on the Estimate screen, you will see a lot of "Retrieve value from table" actions that are very similar to what your trying to do.
If this is not the problem that you are having, check to see if you have any conflicts under the QuickBooks tab.
For the campaign information, I think what you are looking for is as follows;
You setup a new customer and on the Customer List screen, while setting up the user information, you selected the campaign “Florida”. Then you go into the Sales Order(SO) screen and create a new SO for this client.
At this point I think you are expecting, that the SO is automatically linked to the campaign you assigned to this client on the Customer List screen.
Method currently does not do this, but with some small customization, you will be able to get this automated.