for the shipping, you would need to add columns to the products table and the eCart object for the height, width and length of the packages.
in the add to cart buttons, bind the cart height width and length columns to the products recordset height width and length columns.
Then in the shipping rate lookup behavior, set the height, width and length to use the columns from the cart.
for tax, when you run the checkout wizard, you will have the option to set up the tax rate for Tuscon