Tax/form questions

My client needs to charge sales tax only to her California clients but she would prefer not to use the login or address forms on her site. She feels that the need to complete these forms may inhibit the sales process and may discourage some people from wanting to make purchases from her site.
Questions:
1) Is there a way to track California residents for tax purposes without adding these forms to the checkout process?
2) Is there a way to add these forms to her website but make their use optional rather than required for checkout?
3) Could she up the cart so that the completion of these forms is required only for California residents?
4) Is it possible to add the address form to checkout but not the login form. (It appears that both forms work together and that one cannot be added without the other.)

This is very helpful Nicolas...thank you.

In Display->Custom fields, for the "address_country" and "address_state" fields, how can I specify "United States" and "California" as the default values? I am not able to find these choices in the drop-down lists.

Hi,

Have you disabled the United states in the "Zones" menu of HikaShop ? Thanks to check that.
And for the custom field you have to change first the value of the country

I got it Xavier...it's working now...thanks!