andykeller:

Account Field Synchronization:

If QB Billing Address is Blank = Billing Address in Account in Salesforce will be used.
If QB Shipping Address is Blank - Shipping Address in Account in Salesforce will be used.

Yes this is correct for a new Account in Salesforce.

andykeller:

Contact Field Synchronization:

All of the contact fields such as Phone, Fax and Email are from the contact where Primary Contact Field = True.
I notice that the Account Fields also have Fax and Phone.
If I update the phone in Account will it update in QuickBooks and overwrite my existing Phone field that was populated out of the Phone field in Contact?

Yes the main Account fax/phone number are used when synchronizing from Salesforce to Quickbooks.

andykeller:

Opportunity Field Synchronization:

If QB Billing Address is Blank = Billing Address in Account in Salesforce will be used.
If QB Shipping Address is Blank - Shipping Address in Account in Salesforce will be used.

If there is no QB Billing/Shipping Address then it will be populated by the current billing/shipping address for the customer in QB automatically.

andykeller:

Opportunity Field Synchronization (cont):

If terms code is different than the terms code at the account level, does it only apply to this order?

Yes, there are separate terms codes per transaction and per account. These are treated independently.