Is there a way I can get it to select a certain Tax class automatically from Tax Class to Products Price (Net): i.e. without having select the Tax in admin via entering products?
1. Find out the tax class ID number in Admin> Locations/Taxes> Tax Classes
Click on the desired tax class.
look in the URL for &tID=
grab the number from that (likely 1 or 2 or something)
2. Admin> Catalog> Product Types
Select the product type you're using, and click Edit Layout
Near the bottom of the list that appears, choose:
Product Price Tax Class Default - When adding new products?
and enter the tax class ID number you obtained in step 1 above.
Ta-Da! Next time you add a product, the tax class is pre-selected.