Can I use HikaShop? : Wholesale/Retail pricing

If you just want to offer lower prices when a customer order a product in big quantities, that's something already possible. You can already add several prices for a product and limit each price to a minimum quantity:
10€ => 0 and +
9€ => 10 and +
8€ => 50 and +
etc
Now if you want to limit products/categories or prices to some joomla groups. It's not yet possible with HikaShop. That's something we want to do in the future by supporting joomla ACL.

Yes. It's now possible. In the Business edition, you configure access levels to the prices of your products and variants so that only some groups of users can see a price. On joomla 1.6 you can directly manage your groups of users within joomla's groups manager. On joomla 1.5, you will have to use DJF ACL as there is no groups manager.

It depends where you live. Once you enter your address, the system will update the display of the VAT if necessary.

So you won't have to pay it.

You can only pay in euros or USD. That doesn't mean that you can't use your australian card. It's just that you will bear the conversion from AUD to EUR or USD instead of us.

For the VAT, that is really strange, it works for every one else... I've just updated the version of HikaShop on our website as I recall that there was some VAT refresh issues in previous versions...