We have recently upgraded from Group Edition to the Enterprise Edition and I am tasked with developing a better design approach as we have a lot more functionality extended with this version.  Our earlier Group edition supported our business processes through having our customers set up as Accounts and the Contacts shared a joint role between persons associated with our customers and our Driver Base.  Opportunities were used to house all of the loads (our product...which is a service) that were developed throughout the sales cycle and Accounts (3 at a time, Billing Account-Pick Up Location Account-Delivery Location Account) and Contacts (Person requesting the move, Pick up contact, Delivery contact and then our Driver who actually delivered the product) were all a part of each opportunity. 

The limitations that we had with this was that there was not a way to auto populate a Ready Date for the driver inside the detail contact that came from the opportunity.  Additionally, I would like to have work flow rules that cross objects.  I do not want to lose any of the Contacts functionality or tie ins, however need to figure out the best approach for having the opportunity drive behaviors downstream.  There is already several look up fields associated with both the Account and Contact objects, however I need a way to feed informatin back upstream from the opportunity after it has been updated.  I do not want to have a look up field on Contacts as this would require additional steps and convolude the process. 


Does anyone have any ideas for this? 

Similarly, I am interested in seeing if anyone has used the quotes object for invoicing?  If not, what other suggestions would you have for invoicing and a good tie in to Quickbooks for real time updates back and forth.