Need to build a SP 2013 Workflow in Designer that Derives Due Date

Hi,

I'm trying to use SP Designer 2013 to build a 2013 workflow.  It involves reading an order date from one list, a terms value from another list, and then calculating the Due Date in the first list.  So, if the order date is 4/3/2013 and the Terms value is 15 (net 15 days), the workflow needs to populate the Due Date with 4/18/2013.

Questions:

1.Can this be done in Designer?

2. If it cannot be done in Designer, how would I setup the workflow in VS2012?  Do I set variables for the payment terms value and the order date value? 

3.  What date function should be used to add the appropriate number of days to the order date?

Thanks,

Sid