Hi geostar,
For questions one and two, you can edit the language file in HikaShop > Configuration > Languages, and edit the language wanted.
You can see the FAQ here:
http://www.hikashop.com/en/support/documentation/faq.html#translation
3. You can set the default Zone in HikaShop > Display > Custom Fields > Address_country.
4. Still in HikaShop > Display > Custom Fields, in the listing you can set if the field must be required, and displayed.
5. I don't see VM_TAX_3 in my translation file, I think it's the name of your Tax Category.