Virtual Products, PayPal, & VM 3.0.12

[jk15060]

I have both PayPal Express and PayPal Standard configured for a single product on a test website.  Both payment methods point to the PayPal Sandbox until the process works as expected.  I am running Joomla 3.4.5, VirtueMart 3.0.12, and PHP version is 5.6.15.

I am very new to VM, especially as it pertains to virtual products for sale.  I've got a few questions about the Payments & Shipments.  Please point me in the right direction if these questions have already been answered.  I'm just getting a bit frustrated at this point.

1)  Can Virtual Products be configured in VirtueMart 3.0.12 or will I need an additional extension to handle downloadable products? 
      I've added a location in the SafePath where the downloads are stored, but

2)  Is it best to require an address (and registration) on the website AND configure NC Tax in VirtueMart or can VM handle tax information being calculated in PayPal, along with capturing a customer's address?
     Selling products in a specific state in the US requires taxes be collected.  I have the tax information configured in the PayPal sandbox, but there doesn't seem to be any taxes applied when I test the shop. 

3) I continue to get errors with my testing and cannot seem to find a solution for these errors.  This error appears when I click the Checkout with PayPal (Sandbox) from the cart. 
     I have tried Checkout settings (configuration):  Enable Automatic Selected Shipment to None and then to No Preference and still get the same error.

Error
Programming error,Paypal expresscheckout: virtuemart_paymentmethod_id is 0
Programming error,Paypal expresscheckout: virtuemart_paymentmethod_id is 0

Notice
An error occurred. The payment has not validated. Please choose another payment

Thank you for any help that might be out there today. 

[GJC Web Design]

virtual products you need a 3rd party plugin..  e.g.  http://extensions.virtuemart.net/products/shipment-for-virtual-products-detail

2)  tax within VM can only be calc. if you collect the address.. the address is passed to paypal - registration isn't nesscesary

3) I don't know.. never used PP Express