Regarding the prices, you can change the price display options of the Display tab of the configuration and of each one of your menus/modules (via the menus Display->Content menus/modules) so that either the USD price is not display.
You should use the currency switcher module so that your users can switch from one currency to the other.
Regarding the fact that the final total is only in USD, that's the only possibility if you want to use PayPal. The price has to be given to PayPal in USD because PayPal cannot process INR.
In my opinion, the best would probably be to use another payment gateway which can handle INR. It would be less confusing for your customers. You should check CardSave or AlertPay. They handle a lot of currencies so maybe they handle INR.
For the last error, you can look at that documentation:
www.hikashop.com/en/support/documentatio...l-error.html#address